Self adhesive bra size ??? HELP NEED ANSWERED 2DAY!?

I am ordering online one 2 of the self adhesive bras and i was wondering on wat size to get it comes in A,B,C ... i am a 32 aa (ugh) if i get a c would it make my appear bigger or would it just be heavy and if i got an a would it help create because it is tighter ? please help i need to know because i am expecting them tomorrow and need to know to day thanks !