Tips for Ovulating?

I always get a surge but I’m not sure I’m ovulating. My opks will be dark for a day maybe 2 max. I have one child (metformin baby). I take 500mg metformin and I haven’t become pregnant again. My partner and I are ready and this would be his first an smh second. Any tips on what to do? I’m in my late 20s and my man is 30.