How do you choose between a small and a medium Wacom Intuos graphics tablet?

I'm a high school student who is extremely intrigued, curious, and enamoured with the idea of using a graphics tablet for art. My parents are more than willing to buy me the medium size if it assists me in my art journey. In fact, they're forcing me, well, guiding me towards choosing the medium over the small. I'm perfectly happy with the small size though. Actually, I'd be absolutely ecstatic if I received the small graphics tablet. 

I'm leaning towards the small because of practicality, portability, and price, and, it seems like buying a smaller size with a smaller price is a smaller commitment. My parents want me to disregard the sizeable price difference between them though when deciding which one I really want or which one would be best suited for my needs. 

The small Wacom Intuos Art graphics tablet (152x95 mm, 14 440 mm squared)
- Officeworks: $126
- JB Hi-Fi: $148

The medium Wacom Intuos Art graphics tablet (215.9x134 mm, 28 930.6 mm squared)
- Officeworks: $209
- JB Hi-Fi: $288