1st IUI set for 12/18

We are set to do our 1st IUI next week. I'm so anxious and a little scared. I'm 35, my husband is 32, no kids for either of us (yet...) We have been trying for over 1 year. Had an HSG in July which was "perfect" according to Dr. My husband had his testing and everything was good with him too. We have done 3 rounds of 50mg clomid and this will be 4th round of 100mg ( so 7 total). My periods have been crazy, basically non existent while taking the clomid. Last month my progesterone was 39.8, no period just brown spotting and some "nice looking follicles" according to the Dr. But still a BFN 😕 this month with out he clomid it dropped back down to 7 😔 Any input on your experience with IUI would be greatly appreciated! Any success with 1st round? Side effects of meds? Is it as painful as an HSG? Anything at all, I've read a lot of posts regarding IUI and women's experiences seem to he all over the map, which makes me even more anxious....