I started a new birth control (pill) about 2-3 weeks ago.

I had sex with a condom but it came off halfway (this was 2 weeks before I got on BC.)

I had unprotected sex about a week ago but he didn’t cum. I’m 6 days late for my period, but I keep having very light brown blood. Yesterday I had a tiny bit and today I’ve had a tiny bit.

Is it just old blood, is it from my BC, or is something wrong?