If your bra is too tight, it can result in a bra bulge. The band will be too tight against your skin, which pushes fat and skin outward, creating bumps and lumps under your top. Therefore, a good place to start is by making sure that your bra fits you correctly.
How do I get rid of back fat from my bra?
How do you get rid of upper bra fat?
Why does my bra give me side fat?
If it is inching upwards, it could mean that the band size is wrong. A smaller band and cup size will result in your breasts spilling out over the cups. Secondly, check the cup size. Cups that are too small will result in spillage, so try going up a cup size.