1. The center gore should always lie flat against your chest.
There are a few, rare exceptions, such as pectus excavatum, breasts that are extremely close together (no room for the gore to fit between them), some soft cup nursing bras, and sports bras.
However, for the most part, having the gore sit directly on your chest is one of the most important indication of good fit.
2. Bras are not supposed to hurt.
3. You do not have back fat.
Make sure you scoop and swoop all this tissue into the cups in order to determine if your bra is fitting correctly.
4. Band size is indicative of your underbust measurement.
5. Cup size is not bra size.
Cup size is simply the difference between your bust and underbust. And yes, there are more letters than just A, B, C, D, and DD.