Advice is welcome

We have been TTC seriously since January this year and so far no BFP. We have timed BD to the best of our ability. I have a aolid 27-28day cycle,i hqve been using opks and get my lh peak every month around CD 12-13. We have a 4yr old already and a miscarriage last year Jan at 5weeks. Could it be that I'm not ovulating? I started taking Pink stork fertility this cycle. Anyone who has succeed with a BFP please help me out with advice. My last hope is to go back to my obgyn and ask for Clomid but last time he said he wouldn't prescribe it because it seems I'm ovulating(ultrasound confirmed)on my own and very regular cycles. Sorry for all the rumbling...I'm just feeling lost,defeated and mad at my own body.