Wrong cup size đŸ˜©

Ok so let me start by saying that my grandmother raised me instead of my mother and she really didn’t teach me anything that every woman should know. I figured most of it out on my own. I am also an adult and have my own child now (so no I’m not trolling) but I have always had such a hard time finding bras that fit... that band is the correct size. I’ve even been measured at Victoria’s Secret. I was told I was a “B” cup but it was always too small like side boob falls out of the cup. So after I had my daughter I went up to a “C” cup but it’s too big... I really don’t know what to do being uncomfortable in both cup sizes. Does anyone else have this problem?