Seeking some answers

Hi all, I'm new to the whole forum thing so please be gentle 😊
I'm 37 years old and my partner and I have fallen pregnant naturally 3 times in the last 12 months with all pregnancies ending in early miscarriages all around 6-8 weeks. So we visited our closest Reproductive Medicine clinic and got started with IVF in May. We were able to have 3 embryos that made it to blastocyst stage. We were advised to transfer 1 without doing any pregenetic screening. This cycle failed with my period coming the night before my blood test. I have not had any possible explanation for the failure explained to me by our Repromed Dr. We are now having the other 2 embryos screened for genetic abnormalities and are awaiting results. My concern now is that although I ovulayed in July (around the 17th) it has now been 37 days since my last period. Is this normal? I've spoken to a nurse at Repromed and she advised to give it a few more days and if nothing comes they will arrange bloods. Sorry for such a long first entry but anyone that can share some insight it would be appreciated. 😊