I've had trouble finding bras to fit too, I thought I had trouble before but now that I'm breastfeeding it's almost impossible. I was a similar size to you. The bras I bought when I was pregnant don't fit anymore, I got bigger in the cup, and smaller in the back, so I agree with not spending too much now because it's hard to judge what your body will do.

I went to mothers direct and got fitted there about a month or two after DS was born and they were so patient, I think I almost tried on every bra in the shop! I found one that finally works, it's made by triumph, they do bigger cup sizes in a 10, and it's not too nanna-ish either. It was pretty pricey ($80 i think) but so worth it.

I then found them at trade secret for $20! So glad I only bought one originally.

Good luck!