Vaginal Expansion/Contraction

So I just discovered something interesting and wanted to know if anyone else relates? So I know that vaginas are like rubber bands, and the expand and contract to what’s inside of them. The first guy I had sex with was 8 inches, and we had sex for two years. It got to the point where his dick did not hurt and I could take the whole thing. When we broke up, I started dating a guy with a five inch dick, which worries me because I was used to 8 inches. But now when we have sex it hurts at times (good hurt) and feels almost no different. Maybe this is just me?