Iui no trigger now?

Jo • Both 41...TTC for too long
So dr called &said not to trigger but having iui on Monday morning. Took Femara cd2-6 went today have 4 follicles in left &0 on right side. 
​Measurements were 20-16 
​I'm 40 ttc for a year. Why wouldn't I trigger?? Already had failed iui on clomid. And I'm paying oop! 
​Anyone know why or has heard of this? Any success?