What could this be?! HELP!

Lindsey

I need y’alls input. Been TTC for a few months now. My breasts have been severely sore for 4 weeks. I had my “period” but it lasted 3 days instead of the usual 5. Was 2 days late and only 1 heavy day instead of 2 or 3. Took a pregnancy test and it was negative but my boobs hurt SO bad and the ring around my nipples seems a little darker. Anyone else experience this or have any input on what this could be?! Please help!