Spotting or Period?

Heather
The last time I had sex was on the 14th of July then again on the 21st. I've been waiting for my period and I am a few days late. Today when I went to the bathroom I thought I started my period but I only see the blood when I wipe. It hasn't gotten on my under wear or felt like I'm bleeding. So I only see blood when I wipe. Which isn't really normal for me. Help!