Natalie, it's no laughing matter actually regarding how big they will get as I totally sympathise with your concerns. Un pregnant I am an E cup, pregnant I went up to a double F. Then when the milk flooded in I was a J cup and miserable. Also your breasts just seem to smother your baby, so feeding is always a two handed affair, none of this comfy business you see in magazines. I eventually settled back down to an F after a couple of weeks and then an E cup again.
The best bit of feeding equipment you could get is an L shaped pillow, if you are going to end up with gigantor breasts. It helps elevate your baby towards the breast, so less stooping on your already strained back and provides a rest for your arm, you'll have to help baby not get smothered by your boobs.
I;m making it sound horrendous aren;t i? Honestly it's not I fed both my boys for a long time.