For sure I'm not pregnant? ?

Basically, I have managed to scare myself into thinking I could be pregnant. I read online that its possible to get pregnant from dry humping. Me and my boyfriend have done that a lot. However, although he normally ejaculates, I don't notice any wet marks on my own clothes. We always both wear pants and underwear. I know I'm not pregnant. I know that. Well I know it's nearly impossible. I'm currently on my period and it feels totally normal. I just need some peace of mind that I'm totally not pregnant, can anyone tell me a for sure sign I'm not?