My periods are usually irregular: 1-4 days late, never on time, very heavy and last 5-6 days.

My last period was odd:

On time exactly, not as heavy as usual and only lasted 4 days (very rare). I also noticed on the last day that my right breast grew a noticeable amount. It just feels heavier/fuller.

Why might that be?

My bf and I have been starting out sex without condoms a lot lately but we always finish with one on.