As his friends went through puberty, Neil Brennan remained stubbornly boyish and undeveloped. By 18, he was desperately anxious … would he ever catch up with his peers?

The bouncer looks me up and down. Then, as he beckons the rest of my 17-year-old schoolmates into the nightclub without hesitation, he looks me up and down again. He calls another bouncer over. They take it in turns to look me up and down. Everyone in my school year looks on from inside the club, passersby stop to gawk. My head turns so red that it threatens at any moment to blast off into space. “What do you think,” the first bouncer asks his pal, “does he look 18 to you?”

The truth is, I don’t. Not even close.

Puberty came to me so late that until my last year of university, I looked about 13. Think of Daniel Radcliffe in the first Harry Potter movie, all high voice and cherubic face. That was me for the best part of a decade. I would shy away whenever my parents wanted to take a picture of me. Few teenage boys want to be reminded that they look like Sue Perkins.

The NHS “Puberty – Complications” page says that if a girl shows no sign of breast development by 13, she may be suffering from delayed puberty. For boys, it’s the testicles that are checked. If there’s no development by 14, doctors can look into whether puberty might need a helping hand. More often than not, though, it seems their advice will be to let nature take its course.

The trouble was that my testicles had more or less developed just fine, thank you very much. It was the rest of me that refused to grow up. I was always a little small for my age, but that was never a big issue, even after some creative bullies successfully tested the theory that I was small enough to fit inside a bin upside down.

My dad is 5ft 8in, my mam 5ft 6in – I was convinced I’d come right eventually. In the meantime, I was funny enough to get away with being the smallest kid in class. By which I mean that I made jokes about the obese kid to deflect attention from myself.

Suddenly, all the other boys shot up, their voices got deeper, their bodies hairier. The PE changing rooms became a natural history documentary for me, at once fascinating and terrifying. Worst of all was the realisation that girls loved this stuff. When I overheard a bunch of them rating the broadness of other boys’ shoulders, I despaired. When were my shoulders going to broaden? When were girls going to objectify me?

Neil on his 18th birthday.

My family has always been close, but a lot of that’s expressed through taking the mickey out of each other. Maybe that’s why I didn’t confide in my parents straight away. It was embarrassing enough to be fighting this private war with my stupid, stubborn body. I didn’t want anyone else making fun of me for it.

It wasn’t just the good stuff of puberty that I wanted. I actively sought spots and would wolf down greasy food in the hope of attaining some. The thing that I craved most of all was a prominent Adam’s apple. A classmate had one that looked like he had swallowed a golf ball that got stuck. I would find myself staring covetously at it as it bobbed hypnotically.

Approaching my 16th birthday, my friends started to get part-time jobs. Lying about my age on the application form, I got work sweeping the floors of a supermarket. One day, the manager demanded to see my birth certificate.

After a cry in the baby food aisle, I did the only thing I could. Using liquid paper and a photocopier, I forged my certificate. But things were about to get worse.

Facebook Twitter Pinterest Neil, centre, aged 19, with friends.

My friends stopped hanging around with me. They wanted to sneak into pubs, buy cigarettes, meet girls – I still had trouble getting into 15-certificate films. They bullied me out of the group, using pretty horrible tactics to let me know that I was too much of a kid to be seen with them. I was lonelier than I’ve ever been.

In my final year at school, a Catholic priest visited us to talk about joining the priesthood. I genuinely wondered if this might work for me, as it would give me an excuse for why girls never took an interest in me. Then I remembered I was an atheist. So instead of talking to God, I did something I should have done a long time before: I talked to my parents.

I told my dad about my concerns first. His advice was a mixture of the positive and the practical: he would happily take me to the doctor, but advised that first I should start to dress older. So it was out with the baggy jeans and loose hoodies and in with the shirts and smart trousers. Well, jeans – I didn’t want to look like a bank manager.

I told Dad how badly I wanted an Adam’s apple. He responded in the best way possible, telling me that it was one of the stupidest things he’d ever heard. Just by voicing my worries, I started to realise how silly a lot of them were.

My parents took me first to our GP, who gave me some vitamins and told me not to worry. Nothing happened, but my Omega 3 levels were through the roof. Next, they took me to a private hospital, where we met an endocrinologist.

Sitting in the supportive consultant’s office, I knew straight away that this was exactly what I had needed all along. After speaking to me and my parents, he asked them to leave so he could examine me on my own. He had a poke and a prod, and asked for details of my “private habits”. Mortifying as it was, I didn’t hold back, determined to get this thing sorted.

Once we were done, he brought my parents in. He was convinced that everything was starting to develop but also offered blood tests to rule out anything more serious. Even if he wasn’t telling me anything I hadn’t heard before, it was a relief to hear this top doctor (and very tall man) promise that at some point my body would get its act together.

But our appointment wasn’t over yet. Oh no. He proceeded to outline to Mam and Dad all the information gleaned during our consultation. He was happy with my testicles. My penis was developing nicely. And my masturbatory habits were perfectly normal. They were, naturally, delighted to hear all this. And right before lunch too.

Facebook Twitter Pinterest Neil today, aged 29. Photograph: Sarah Lee/Guardian

The truth is, even after he ruled out any major hormone issues, it was still more than two years of waiting. The bouncers outside my graduation party were still to come, as was missing all of the socials at the start of my first university year. On my 18th birthday, I was turned away from my local pub because the manager reckoned my passport was a fake. Well, I did have form, I suppose.

When I was 20, nature finally took its course. On a four-month study programme in Australia, the skin on my face toughened and then sprouted tiny hairs, invisible to anyone but me. I stopped having to pretend my voice was deep, it just was.

I came home from Australia with a new confidence and didn’t look back. I graduated and made a move on a girl I had fancied for years. It was like getting over a cold, one day everything was as it should be and it was hard to dwell on all the rough times that had gone before.

What was harrowing at the time now seems hilarious – and that includes my parents’ photograph albums.