All I want is my period! I never thought I'd say that

Mandolin
I'm afraid I might be pregnant. I'm 17, and I had unprotected sex twice this month, and my period is 9 days late. Last week I had PMS symptoms, but never bled. Now, my symptoms are reduced, and I'm still not bleeding. I've tried to masturbate often this week in order to get some contractions going and hopefully kickstart my period, but nothing happened. 
When my period was 3 days late (a little early) I took a HPT, and it was negative. But that was relatively early. 
I'm not necessarily stressing over it, either. I'm a little worried, but its nothing I can't handle. I just don't know what to do.