Missed period post IUI. Of my period?

I had my IUI done on 30th April with Letrozole and a trigger injection. Today, 18th May, I took a urine pregnancy test, and it was negative. I have been taking Susten SR 300 and Duphaston 10mg as advised. I haven’t experienced any symptoms and it feels like my period might start anytime soon. I visited a doctor yesterday, and during the pelvic scan, she mentioned that this cycle did not result in pregnancy and that I should be getting my period soon. The endometrial thickness was 8.9mm. Is it true? She asked me to stop the medication but I wanted to reconfirm. I just wanted to confirm: Should I stop taking Susten and Duphaston now? Do these medications delay the onset of my period? Please let me know the next steps. Thank you for your continued support.