This has been a busy day for me [hgrin]
OK, first things first is to make sure you're actually wearing the correct size. An AA cup would mean you measure exactly the same under your bust as across the fullest part. I would guess that you need to size down in the band and up in the cup and try some balconette padded shapes.
Measure under your bust (hold the tape tight) to get your band measurement. Do not add on any inches to this measurement. Then measure across the fullest part of your bust. Each 1" of difference between the two measurements equals a cup size.
So, let?s say you measure 30" underneath and 34" across? That would give you a starting point of 30D.
The best way I've found to test the band size is to put the bra (in your case a 30 back) on back to front. If you can breathe but if feels tight and you can only fit two fingers underneath the wire at the front, then that's the correct back size for you. If it's so tight it's unbearable then go up a size.
Once you've got the back sorted, it's time to get the cup right. The cup will differ much more between brands and styles than the back (IMHO). Turn the bra round the correct way, lean forward and using your hands, scoop all your breast tissue into the cups (make sure you get all the flesh from round your back and under your arms in). The put the shoulder straps up and adjust as necessary (not too tight as it's the back that should be doing most of the supporting work). If for example, you've started with a 30DD, you will probably find that after scooping, you have some bulging over the cup and quadraboob going on! This means you need to go up one or more cup sizes. Keep going up through the cup sizes until all your breast tissue is firmly in place.
Boobs that are fuller at the top usually suit plunge and those that are fuller at the bottom (like mine) usually suit balcony I'm not a fan of the unpadded full cup style but many love them.