In addition to what's already been said, your age is most definitely on your side. It is very unusual for someone as young as you to get breast cancer, so take heart from that.
The waiting is absolutely the worst part, so be prepared for an emotional rollercoaster. Do what you can to keep busy, which I'm sure won't be difficult with a baby to occupy!
Try and stay positive, as your GP has already indicated cysts which are perfectly harmless pockets of fluid.
Keep us posted, and come on here whenever you need a good rant, or a bit of a shoulder.
Take care, Mel. xx