penicillin and periods?

I got strep a week before I was suppose to start my period. I was on 500mgs of penicillin twice a day and I'm only 90 pounds so it was a lot. I've missed my period. It's been a week and a half since I was suppose to start it. I had all my normal symptoms but never actually bled. I'm very sexually active but my boyfriend is close to infertile. I just wanted to know if anyone has had experiences close to this before I go buy tests.