I'm 18 and I need some advice.?

My boyfriend and I have been in a committed relationship for over 2 years now. We restrained from ual activity until we were both ready as we were virgins. I am on Yasmin 28, take my pill at the same time every night and we use a condom as well. We started having every so often but we haven't since one particular time. He usually pulls out before he s, even with a condom on but he was too late this time. When he tried to pull out after, the condom was not on him. After looking around, we found it was hanging out of me. It wasn't the full way in, just the tip but I'm still scared. I know he will support me no matter what and he is aware of how nervous and stressed I've been about this but I just need some reurance. What are the chances I could be pregnant? Please help.