Possibly pregnancy?

A couple days ago I was spotting on and off for about 2-3 days .. I know spotting is common in between periods but I have never spotted before .. Now about 3 weeks ago almost me and my bf had sex and he came in me each time .. But I wasn't on my fertile window or ovulating I don't think (I'm not really sure when I ovulate since my periods are so irregular?) is there a high chance of me being pregnant?