HELP ME! I am only 17 and afraid I am pregnant!?

Okay a little over 1 week ago my boyfriend and I were dry humping (he had underwear, I didn't). He did not ejaculate, might have had precum but he had urinated since the last time he did ejaculate and idk if it when through his underwear at all. It was not for long at all because I got scared, and am still a virgin! I have no idea if I was ovulating because my periods are super irregular and usually go 1.5 to three months without one. I am really scared and told my sister about it today but she yelled at me and I started bawling. Since then I have felt sick. Is it morning sickness? What are the chances I am pregnant cause I am so scared :(