First IUI was a fail :(

So my journey has been going on for 3 years. After 2 years ttc we starting doctoring for infertility. We had numerous tests done. Progesterone, prolactin, a blood test to check egg reserve, HSG was done, semen analysis ALL came back with no problems. The only abnormal thung that happens is that i have brown spotting for about 5 days prior to my period. I started with a new doctor about 6 months ago. He thought the spotting could mean that my follicles were not fully developing or that it could just be normal for me. He started me on letrozole and I took that for 5 months with no result. I have always gotten positive opk and my progesterone indicated that I ovulate but he thought this may help me ovulate better. But no positive peg test. So this last month we decided that after 3 years we would try IUI. I had a follicle ultrasound on day 10 which gave me such piece of mind because it showed good results. My follicles were good size and there were plenty of them growing. My uterine wall looked great and ready for an egg. So we did opk every day until we got a positive and went in the next day for the IUI. I was so hopeful that this was the answer. Why shouldn't it work right they can't find anything wrong with us. My husband kept telling me this will work it has to. Well yesterday I got my period and I am devestated. It is so much harder this month because we were just so much more hopeful. I will try it a few more times but now my hopefulness is much less :(