How can I tell if I’m ovulating?!

I asked this in another app and got no responses. Lol.

I had an ultrasound back in December where they found a fibroid (which they knew I had from my last pregnancy) and now cysts on my ovaries. During which the ultrasound Tech sounded very surprised that I had conceived without medical intervention. My doctor never even called me to discuss the results since it “wasn’t a big deal”. How can I tell for sure that I am actually ovulating? I’m trying bbt but my numbers seem all over the place.