follicle size......HELP

Ashley
I am on femara and ovidrel trigger shot. I went to the office on Sunday for an ultrasound to see if I had mature follicles (cd 12). I have one follicle 24cm on the left side. The nurse doing the ultrasound said "oh! I would have brought you back yesterday, your follicle is really big". I was instructed to do the trigger shot that night and come back on tues for <a href="https://glowing.com/glow-fertility-program">IUI</a>. 
Are they doing the trigger shot and <a href="https://glowing.com/glow-fertility-program">IUI</a> too late? This is my third round of <a href="https://glowing.com/glow-fertility-program">IUI</a> and I'm feeling really hopeless. On one hand I feel like they are the experts and know what they are doing, on the other hand I feel like they might be timing the whole thing wrong! 
Anyone have experience with <a href="https://glowing.com/glow-fertility-program">IUI</a>? How big were your follicle(s)? Do you think their timing is off???? 
Usually when I post, no one reaponds, but I really need some advice and encouragement!
Thank you!