Irregular periods and CTT

Robin
I'm day 38 in cycle and started my period today. I've been trying to figure out when ovulation actually is occurring, but seems impossible. I've measured BBT for months and did ovulation tests. Nothing seems to be accurate. We are going back to our fertility doctor next month. Planning a round of clomid. Anyone have experience with irregular periods and clomid? I was a Christmas announcement SO BAD.