IUI with new meds; Letrozole and Ultrasounds

I recently went in for my fourth ultrasound for a possible third IUI to find out that I can’t trust the OB I currently have. She only had to using Ovidrel, and never offered any other ovulation aiding meds as she stated that because I had issues of Clomid I would have issues with others.

My new OB that I recently switched to has suggested that I start letrozole. Can anyone give any insight on psychological mental changes while on letrozole?

Also, my old OB only had me doing a follicular scan at the beginning of my ovulation window. This new OB wants me to do 2 to 3 scans per cycle for best results. Can anyone give any insight on how many ultrasounds they do typically per one IUI cycle?