Trigger shot day

At 9:45 I have an ultrasound and trigger shot. I'm embarrassed to admit I don't know what the shot is of or how it works. I think it's FSH and it controls the timing of ovulation more precisely than if we just wait for the LH test to turn positive. It's day 11. I think now I go back in 2 days for the IUI. Of course, if we don't see any follicles on the ultrasound, then theres nothing to trigger. I think that's unlikely since I have been ovulating on Clomid. I haven't had any cramps this month yet to suggest ovary swelling, but last month it was just one day. The guy I've been seeing is gone for 3 weeks. Well, sort of gone. Anyway, he is clearly not interested in daddy duty, so there's no reason to hold off and hope he comes around.