Clomid, Estradiol and Prometrium help

I've been trying to conceive for 15 months now. 3 failed Clomid attempts and 2 failed IUI's.

My doctor called me today. I am starting Clomid again days 3-7 at 50 mg like I've been doing. New this month he's adding Estradiol 3 mg twice a day, day 8 through the morning of day 12. Then I start Prometrium 200 mg daily at night starting day 17 and will be a continuous pill if I get pregnant through 12 weeks. I'll also have an IUI this month with positive ovulation test. Has anyone had this regiment before? Success rate?