This is the Boob or Bust Fit Check helper. If you haven’t already done it, please check the The Band Test first
Not filling the bottom of the cup

Filling the bottom of the cup with wires in the boob crease
Make sure you have scooped & swooped, and your boobs are sitting in the bottom of the cup if possible. The wires should sit right in your boob crease. (light purple line)
If your boobs don’t sit properly in the bottom of the cup
If you’re getting overspill elsewhere – go up in the cup size
If you are filling the cup elsewhere but not getting overspill – look at styles with more projection, particularly in the lower half of the cup. The group will be able to give you some ideas on bras to try.
If you’re not filling the cup and when you pull the cup up your boobs drop to the bottom of the cup – go down a cup, it sounds like it might well be too big.