Advice needed please

[Emmyh80s]

I had my first round of iui in April which ended in a bfn. My iui was with trigger injection of ovritelle. I wanted to just go straight into my second round when my period started and was due to ovulate according to my app and previous months on Sunday but my opk is still negative today and everyday since last Friday when the clinic suggested testing. Has anyone else had experience of delayed ovulation after first round of iui? I’m just confused as I was very regular before my iui as I was checking every month leading up to it to get an idea of timings. Thanks in advance for any advice