What's wrong with me?

Hi , I hope some one can help. I had an IUI on April 17. had 5 neg HPT, Neg blood test. (so i guess i'm definitly not preggers)
But AF is still 2 weeks late and I can't figure out why? I've never been late more than a day or two. Had an US ( before the blood test) doc said uterus linning was thick, no cysts, but blood test said not pregnant. Has anyone had simliar experience. I was on clomid before my IUI. With my last IUI 2 years ago I was on Femara with out a problem, could it be the Clomid? I 'm on blood thinners from a prevous DVT so I don't think they can give me anything to jump start AF.Any ideas on what's wrong?Please help.

[Trudy80]

Just to have my imput, i have PCOS and had injections to get me ovulating and hcg hormone injection given once i was about to. however i was on clomid b4 i started injections and found for my body they were not successful and i had to take a tablet to induce my periods to start again as it sent them past the af expected date by at least a week. it is disheartening to know you go so far over and no baby is there. that is the absolute worst with fertility drugs and ttc....The horrible waiting game! i look at the end result..BFP!!!! and 9mths and a baby for the rest of your life.  Goodluck. hope i have not further confused you!