My boyfriend and i were dry humping we both had our underwear on, later on he took his underwear off and a few minutes later he cummed on my stomach, i was still wearing underwear (very thin) is there a chance of getting pregnant?

No risk, no worry. You'll never conceive unless a partner ejaculates in your vagina, or perhaps at the vaginal opening. But you're obviously very close to having intercourse, so don't take chances. Get on proper contraception, like pill, insert under your skin, or IUD. Also use condoms to protect against STIs.

Pregnancy is not possible in above circumstances. Contraception remains otherwise key in avoiding undesired pregnancy and associated anxiety when intercourse becomes possible.