If I used a condom whislt having sex and he ejaculated in the condom, then we used another condom after but it slipped off in me could I be pregnant, I'm not on birthcontrol

Possibly

Any time you have sex, protected or not, you run the risk of pregnancy. No form of birth control is 100%, especially if not used effectively(condom breaks/slips off, late/miss a pill, etc. ) you'll just have to wait and see