To trigger or LH Surge

Does your Doctor recommend trigger or natural Lh surge?

We are on our first IUI cycle. I do not have ovulation problems. I still took a clomid 100mg. My doctor did an ultrasound on cycle day 3, 10 and 14. I had three follicles on CD14. One at 20mm, 16mm and 11mm. They did a blood test on cycle day 14 (Friday) and decided that I should wait for some more time. My home opk turned positive on CD16. I had my IUI Monday. But this time the doctor did not check the ultrasound. So I am not sure how many follicles I had. If it does not work this time, I want to try IUI one more time before moving on to IVF. Should I ask my doctor for trigger instead of natural Lh surge? Are there any side affects? Does trigger give you a better success rate?