Condom broke

Alright so our condom broke for the first time ever Saturday night (and of course I freaked out). It apparently had been broken and we didn't realize so I don't know how long we were unprotected. He always pulls out (we always use condoms too, but his pull out game is extremely strong), and I didn't feel any of it get inside of me or on my body at all. I do, however, know that there is a chance precum contains sperm. We immediately went to Walgreens and got Plan B. My period was due to come the next day (good thing I wasn't ovulating), but I am aware taking Plan B would screw that up. I also started the pill Sunday (yesterday) so that probably threw it off even more. I know no one besides a doctor can give me an actual answer on this but I need something to put my mind at ease. My boyfriend says he's 100% sure I'm not going to be pregnant and he's usually right about stuff like this. Have I done everything I could do? Is it likely at all for me to be pregnant?