am I protected???

I'm a little unsure of what to do right now. So I just switched birth controls and I've taken 2 pills of the new brand. I skipped a day in between the last inactive pill of the old brand and the first active pill of the new brand. Today I had sex with my boyfriend with a condom on but then he took it off for like 30 seconds at the end and then pulled out with plenty of time. I wasn't worried until I realized that he hadn't peed in after the last time he had ejaculated. I'm not sure if he got any precum in me but if he did, that means there could be sperm in it, right? He offered to buy me a plan B but I'm not sure if I should take one or not since I'm on the pill. Please let me know what I should do. Thanks!!!