Condom slipped?

So my boyfriend and I had sex for the first time last night. We were both still minorly intoxicated and thought it would be a dandy idea. We used a condom, I am not on the pill and I tried to be careful but I'm not sure if the condom quite fit right. We both knew how to apply one (personally thanks to this app) and did it properly but when he came he stayed inside. The condom didn't come off, I'm just worried that it slipped? What should I do? Should I take the morning after pill? Am I just paranoid?