Starting Out

We have been married now for nearly 7 years. Hard to believe. We were married at 22 and wanted to enjoy the first years of our marriage just getting to know eachother, traveling, being a bit selfish. We talked some about starting a family - but decided to wait and knew the time would come.
We decided to begin trying last fall and both assumed that as soon as we started trying it would happen for us.
As the months of September, October, November, December, January, February, March and April passed our hopes began to diminish. We were charting and documenting my cycles through daily basal body readings as well and ovulation predictor kits. Through this documenting we noticed that my cycles were 40 days long. I seemed to be ovulating right at the end of that time - so my luteal phase was only 8 or so days long. This did not seem to provide enough time for implantation to occur if were were possibly concieving.
We went to the doctor last month and we were put on Prometrium which is a progresterone supplement. The intention of this drug was to hold off my periods so that my uterine wall would remain strong and in turn allow implantation to occur.
Two weeks ago my temperature and our ovulation kit was showing us that it appeared I was ovulating. The instructions were to begin taking Prometrium at this point and take it for two weeks. At the end of that two week time period we were instructed to take a pregnancy test. If the test was positive we would continue taking the medicine for the first six weeks of pregnancy. If the test was negative I was to get off the medication, get my period, and try again the following month.