Letrozole (Fermara)/Clomid Question

I was on letrozole last cycle and we tried IUI which was unsuccessful. From the ultrasound techs and the PA who did the IUI all commented on my having good mucus, and good lining before the IUI. When I called with my unsuccessful results the doc called back and said he wanted me to try Clomid this cycle. I trust my doc (And I plan on talking to him tomorrow) buuuut everything I've read says people go from Clomid to Letrozole, and I feel like I'm taking a backwards step. Anyone else do it this way? Thanks!