Unsure 😕

My husband and I are TTC so I've been pretty on top of using the ovulation a tests. My cycle has been irregular but last week it said I was ovulating. We'd done the deed before and after but today I have light spotting and some cramping. I'm not sure what this is. Everything that I look up says that implantation bleeding occurs around 4-5 weeks, if at all and there's no possible way I'm that far along. I'm not really sure what's going on