TTC with Letrozole 1st round

My OBGYN prescribed me on 2.5mg Letrozole CD5-9 this past month and told to have intercourse CD 11, 13, 15, 19, and 21. I ovulate on my own but have irregular periods (29-41 days varying) and he believes I ovulate too late. My first round I took the Letrozole in the morning & had no side effects! I thought I received a positive opk on CD13, but my temperature didn't go up until later, so looks like I didn't ovulate until CD16 - which is still earlier than I usually ovulate. After ovulation I felt more cramps and was more irritable and chest sore more than usual. I thought I heard Letrozole increased Progesterone levels, yet reading some other women's stories it looks like they had to have their Progesterone tested again 5-7DPO and placed on Progesterone supplements. My temperature dropped way past the cover line in the middle of my luteal phase (6DPO) and it wasn't implantation as I sadly got my period yesterday! I'm wondering if I have low progesterone after ovulation now. I'm so bummed my 1st round didn't work, but hopeful because ovulation was earlier than normal. Has anyone asked their OBGYN to test their Progesterone level after ovulation while on Letrozole? Or is that only for fertility specialists (REs) to do? Does anyone have any success stories? Did your doctor have to increase your dosage of Letrozole and why?