I can never find a bra in my size D:?

Well, I got measured the other day and I found out I'm actually a 30 B, but I have always been wearing a 32-34 A bra, but the middle of the bra wouldn't lay flat on my chest and the bras moved around too much. The woman told me that I would have to go to the "Little girls" section to find a bra, but when I got there I was disappointed, they only had A's. I suppose my boob size is just a rare size or something XD I looked everywhere! I ended up settling on 32 B's because they sat flat on my chest in the middle, and fit at the time, but when I sat down they had a huge gap in the front. I'm stressed now because I just bought 4 new bras that don't fit. I'm wearing a 32 A right now, but it keeps riding up..help!