Is it possible to get implants to increase from AA to A?

Yes it is possible to insert smaller sizes of breast implants.  If you are over the age of 22, you may want to consider gel implants which have a more natural appearance as well as feel .  You can visit a board certified plastic surgeon and try on different sizes to see which you will be most comfortable with.  You can also do an at home rice test to try different sizes. 

Yes, using small implants would be the easiest. Cup size cannot be guaranteed, but when you schedule an appointment, relay your wishes to the surgeon and see if you can try on 200cc implants to see how they look.

Good luck.