I dry humped with my boyfriend. i was naked and he had clothes on. he did not cum but i later had a light period and nausea. can i be pregnant? no sex

Not from above: From what you describe you should not be able to get pregnant from that incident.I assume he did not have his penis inside you. Irregular periods are extremely common in teenage girls, so that can be expected. Most important, as you are becoming sexually active, please, please be careful! you can easily get pregnant and should not do so until you are ready. Until then, use contraception and condom.

Intercourse: This is most unlikely if he did not ejaculate and sperm was not directly or indirectly deposited into your vagina. Since you may desire to experiment further you should have contraception instruction to avoid any future problems, like unwanted pregnancy or venereal disease.