Could I be pregnant?

I had protected sex (condom) with my boyfriend about 3 weeks ago and he also pulled out before he came just in case.

But my period was supposed to start yesterday and I haven’t really got any symptoms of my period going to start. My periods are usually quite irregular and hardly ever start on the day they’re supposed to so it could be that, but I’m really worried I could be pregnant is it likely or am I being paranoid??