For those using vaginal estrogen- what is your dosage and how often?

I’ve had 1mg 1x a day for one cycle and 2mg 2x a day for this one (IUI was today), starting the day I finish letrozole for 14 days. Vaginal progesterone (100mg) is added two days after IUI.

My lining is perpetually thin so I am wondering what others dosages have been for success.