Confused? bra size?

I'm confused about what bra size I need to wear, and my mother won't allow me to be fitted so my best bet is asking on here. I have two bras, a 34C and a 36C. They're the same bra, the only difference is the band size. When I wear the 34C, the band fits well but it squeezes my boobs a bit. When I wear the 36C, it fits well on my boobs but the band squeezes me and leaves red imprints on my skin. What do I do? What size do I try?