Optimal progesterone supplementation?


I am undergoing an FET cycle and I am trying to learn more about progesterone supplementation. I am taking estrogen three times per day and IM progesterone in oil 1ml per day. I have read so many different things about progesterone supplementation and am confused. My doctor hasn't mentioned anything about following blood progesterone levels and potentially adjusting the dose based on the level. I am nervous because I am obese and wondering if this means I am at higher risk of having an inadequate blood level? Can anyone share what their protocols have been for progesterone monitoring when using IM PIO for FET cycle?

I looked back and saw that in one of my prior failed cycles my progesterone was 15 and wonder if that contributed to the problem.

Thanks so much for any advice!