All this work

I recently went to my OBGYN and I told him everything that was going on . He ran a couple of test and told me everything looked fine . We talk and talk he told me about this medication he was gone start me call Letrozole and I should take it on cd 3-7 and to call him if my period didn’t start witch it didn’t so gave me me medroxyprogesterone 10 mg and gave me some birth control to start I’m confused on the BC part . He told me soon as I get a positive ovulation to call him and so I can come do some blood work . I’m hoping and preying this is the break through I need . I’m like 2 weeks on my period I hate irregular period .