Really odd period TMI

So this month I've been under a lot of stress with work and studies and I've skipped 4 or 5 BC pills in 3 weeks and me and my SO have been very sexually active this month even on days where I forgot my pill. So I skipped 2 active pills in a row and so i started my "period" on Monday. I haven't taken any more BC pills since the day before I skipped 2 in a row so that would be Friday. On Monday arvo I had very bright pink/red colour blood on my liner about the size of a 5 cent coin (Australian) then it went to brown spotting. And for the last 2 days it has been brown spotting, I would say it's heavier than the normal brown spotting on day 1 of a normal period. The small amount of blood that I had on Monday is not the colour of my normal period.  I haven't had any cramping and normally I have lots of cramping the day before and the first 2 days of my period. I don't feel like I've had any PMS symptoms either.

Do you guys think I could possibly be pregnant or do you think it's just because I threw off my normal cycle? 

And before anyone goes and gets judgmental on me about being irresponsible with my BC me and my SO we're trying for kids before I decided I wanted to do this course and we stopped so I could be almost finished before we started TTC again so I could finish the course before being too pregnant. So if I was pregnant it really wouldn't matter at this stage as I only have 5 months until I'm finished.