Am I on my period or?

Firstly, to make this clear, I am not planning to get pregnant.My last period was on July 9th, and my cycle goes around 34-36 days. I was 3 weeks late!I am sexually active, yes. My boyfriend does wear condoms, but at other times, we don't think twice which is a bad idea.Today, September 2nd, I got my period but it is very light (not pink or brown) it's the regular red that any other periods would be but it's not the amount I really want to expect, just a small amount (and getting cramps). I'm not sure because of all the stress I've been trying to handle lately has gotten over my head, and because of the whole 3 weeks late thing, it's freaking me out. I have not felt any dizziness or back aches, no breast tenderness, just regular cramps. Did I really get my period?