Good or bad, what is wrong with me? Another busted cycle:( Next steps, please?

I have been ttc #2 for 18 months. I am seeing my Obgyn. I was diagnosed in February 09 with hypothyroidism, tsh levels above 15. My husband had two SA and both were normal, he has no children. I have had normal tsh levels below 3, for three months now. I have been on 50mg clomid for 3 months now, with progesterone levels the following- 18 for March, 27 for April, and 12.5 for May. My lining has been 12 mm for April and 13 mm for May. I have 26 day cycles and ovulate on day 12 or 13. (bbt, and positive opks)I take 200 mg of prometrium daily. Today endend another cycle, as I am 14dpo and began spotting on the prometrium. What is wrong with me? I have had many ultrasounds and tests, tubes are clear. Will I ever get pregnant? Am I too old? I am 36. What should be my next steps? I am heartbroken today:( Thank you.