Symptoms After Stopping Birth Control?

I stopped taking the pill about 3 months ago and got my period every month (I did not initially have a long delay, my first period came about when it would have if I was still on the pill). I am about 10 days late, but I don't think I am pregnant (2 negative hpt's and I'm not even sure if I had sex during the fertile part of my cycle). My question is, could the hormones now be out of my system causing my cycle to be irregular? Thank you!