Bra size advice

Hello!

I was wondering if any of you could advise me on what to do. I have very small breast I wear a 32 A but recently the bands have been too tight. They fit just right but I do not like how tight they feel on my back.

What size should I try if 32 A cups fit fine but the bands on my back feel tight??

I tried to measure myself and this is what I got:

Bust 32 in

Band: 31 in