I had sex for the 1st time with my boyfriend, we used a condom and he pulled out before finishing, just want reassurance that pregnancy is unlikely?

Yes, it's unlikely: When a condom use used EXACTLY as intended, the failure rate is very low. It is said that only 2-3% of women become pregnant during an entire year of perfectly diligent condom use. Other contraceptive methods may be more effective. For a discussion of contraceptive failures with condom use, see http://goaskalice.columbia.edu/answered-questions/explanation-condom-failure-rates