Clomid & long cycles


So ladies I have pcos started my first round of clomid (50mg) this month on cd 5-9. My gyno didn't want to run any blood tests to see if it worked. She said if it worked it worked...but how am I suppose to know if it actually does or if I have to up my dose. My usual cycles run 45-49 days. My primary care doctor will run the proestrogen blood work for me because the gyno doesn't seem to care to. I believe it's suppose to be drawn on cycle day 21. Is that the case even if you generally have long cycles?