When to go to OB?

I stopped breastfeeding around 3 months ago when baby turned 18 months old and started tracking with OPKs at that time. I haven’t gotten a single positive yet. 😔 I’ve had some bleeding that may be a period, but it was very light and not consistent.

We’re TTC again, but I feel like it’s pointless if I’m not ovulating. When should I see my OB?