[AquaA]

My breasts always get lumpy in the end of my cycle on luteal phase and beginning of my period, then by the end of my period the swelling goes and they get much smaller than usual. How I know that the lumps are just due to hormonal changes is by massaging, usually 5 mins in my massage the swelling goes noticeably down and my boobs get jellylike. You should check for lumps after your period when you're on follicular phase.
Hope its all going well with you x