Letrazole first round 38 day long cycle

I’m TTC for my first and never been pregnant before. I started taking Letrazole 2.5mg on CD3-8 last month and didn’t have a bbt temp spike until CD27 and period came on CD38. I didn’t have scans and didn’t consistently use OPKs but when I did the results were always negative. Does anyone have the same experience? My fertility doc hasn’t asked me to go for scans but has asked me to get a blood test done on CD30 this month when I’m on my second round. Has anyone successfully conceived having long cycles/late ovulation on Letrazole?