why did my pcb not expose properly
You want transparency sheet pressed on PCB as flat as possible, no bubbles or gaps and you want it toner side to PCB. What i mean is you want toner to be as close to UV sensitive coating as possible, otherwise youll get shadows with blury edges. 

Overexposure might be a problem too as UV does get thru toner in the long run. I usually lay two copies of a print for one side of PCB (as ideally aligned as possible of course)

Another opposite thing - you mention you are using a photoframe. Does it have a glass or plexiglass in it? UV is filtered out by glass, you need a plexiglass as it's more transparent for UV.

Edit:
I usually use two copies of artwork and water - wet transparencies want to stick togeather because of water surface tension. The same for "glueing" it to PCB. It's just a matter of pushing air bubbles from under transparency - i use a couple of cotton balls - one hand to hold board in place and other to swipe bubbles to the sides.