Can I get pregnant?

My Boyfriend and I dry humped on the 20th 
I had panties on but he was naked. He took off my pants at one point and rubbed his penis onto my butt 
I'm scared that his penis might have touched my vagina accidentally andI felt that it was a little wet on the side of my vagina 
We did this a day after my period and I took a pregnancy test and its negative but I'm scared there's a possibility that I'm pregnant as I took it too early