TMI, Bleeding two weeks after last period??? Help

So, for the past three days now I’ve been lightly bleeding from my vagina. For some context, I had my last period two weeks ago and I am on the pill which I started to take on schedule every day for 3 months now. I am sexually active, I have sex almost every weekend when my boyfriend comes to visit at times protected and others unprotected but pulling out (we are both tested and clean). But could this be breakthrough bleeding? Or am I possibly pregnant by some strange odds?

Also: the blood started out brown and dry like old blood, but today has gotten redder.