I don't get bra sizing. I really don't. I've read countless things on the internet about bra sizing, but I'm still so confused. Possibly TMI?

I went to Victoria's Secret today to buy a new bra because I had a $10 off coupon, and one of the sales associates measured me and told me that I was a 32C. I've been wearing a 32A for non push-up, 32B for push-ups, and I'm just SO CONFUSED, and quite frankly, feeling a bit dumb. The last time I got sized, it was also at Victoria's Secret about 2 years ago and was told that I was 32A. Nothing significant has changed in my body since then (at least not that I've noticed). I know it's Victoria's Secret so they're not necessarily experts, but this lady today seemed to know her shit. She put me into a non-push up demi cup bra after I was all, "Uhhh...C?!" and measured me again. She said that all of my breast tissue has to fill the cup, so C would be best for me. I get that, since sometimes I have a bit of spillage of boobs on the side, but I really have no idea what my true size is at this point. I don't get how a bra is supposed to properly fit.

I know a cup size doesn't necessarily mean larger boobs, but my boobs seem small. It's not like my band size is changing with the measurement the sales associate gave me...it's still a 32. The C-cup bras I tried on at VS did fit. There was nothing wrong with them. I did end up buying one...but OMG HALP, I'm so confused. I guess I could go for a proper fitting elsewhere since VS *probably* runs small anyway, but I'll save that for the weekend or something. Also, I just tried to measure myself about 5 times using different sites and charts on the internet, and I got a variety of answers -.-

Ugh, fuck ALL dissss noize!