Positive OPK test DAYS after ovulation?

Magdala • STM. Baby boy due August 2019.

my last period was on the 24th of July and I had my ovulation the 3rd of this month. I just used my clearblue OPK and was expecting a O but instead I got a ☺ and I read that you can get a positive OPK if you are indeed pregnant. I'm excited at the possibility I've been cramping all day but I also am too nervous to buy a HPT and it comes out negative like every HPT I've gotten in the past... Has anyone been pregnant and used OPK as a HPT sub?