"i've been off my birth control pill for two weeks. How likely is it that I could become pregnant if I've had sex? "

Possible. Being off ocps for 2 weeks is enough time for ovulation to occur. If timing is right, you could conceive. Make sure you take enough Folic Acid if you're actively trying. Call your gyn if you're considering the.
Possible. You should consider yourself fertile anytime you stop taking the pill. You could be ovulating now!