Ovulation question!?!

Gemma
I came off bc nearly 12 months ago and my cycle has been a bit random since, with very very very light af... Anyway, we're just about to start actively ttc so last month I used opk's.. I got a positive, but I'm still worried that I'm not ovulating as my af if so light it's almost non-existent! Can you get a positive opk and then not actually ovulate??