Tender boobs

I’ve been experiencing tender boobs for just over a week now. I’m not due my period as I am on the pill. However I haven’t had a period since the beginning of December as I went onto the next pack straight away as I’m trying to avoid having a period (i just hate having them). I never get tender boobs before a period anyway, I used to when I was a teenager but it just stopped once and I haven’t had tender boobs since. The only other time I’ve had tender boobs was at the beginning of my pregnancy with my son 2 years ago and that didn’t last long either. Is there any other reason I have tender boobs? I don’t believe I could be pregnant as I haven’t had any other symptoms, plus I’m on the pill and plus my partner pulls out. (I’m well aware that this doesn’t mean I can’t get pregnant by the way) but there was one time over Christmas where he said he was a bit late pulling out🙄🙄🙄