4th iui- not surging naturally

I'm on my 4th iui round. 2nd was successful but resulted in a early miscarriage at 8 wks. I usually only need puregon injection for 7-8 days and I start surging naturally and then take Ovidrel night before iui. This time seems different. I have been on puregon now for 9 days tonight and I'm not naturally surging. I know from my apt Sunday I had 2 follicles at 1.7 and 1.8...is this normal what if I never surge naturally? Feeling confused