I have smaller boobs and experience the same thing, i think mine is down to how much some idiots slap, twist, suck them (so hard they practically suck them off), its made me so sensitive. I cant stand it at all now.
If you dont like it put a little in ya profile (faqs on aw) that whilst you like them being admirared you prefer alot of the attention to be downstairs, as your boobies are really sensitive, that way youve covered your back. If they dont read it, well thats their tough luck.
You shouldnt do anything in this job youre not 100% happy with. X