Progesterone on the Low Side, Can a supplement help me get PG??

[Trying4Number1in2007]

A little background first- I am 34 and suffer from spotting 3-5 days before my period. My cycles are 24-25 days long. In the last year they have shortened. When I first got off BCP about 22 months ago my cycles ranged from 28-31 days. About a year ago they started to shorten to 24-25 days with the occasional longer cycle & shorter cycle once in a while. The spotting started only 6 months ago. I have been TTC actively for 8 cycles & have not used protection in 13 cycles. I have never been pregnant & my periods are normal around 3-4 days with moderate cramping & minor clotting if any at all. No history of any other issues.

I have had CD21 blood work done for progesterone and it was 6.6. My OB said this was within normal but on the low side. My C3 FSH was 5.8. I have been using a fertility monitor & taking my temps. I have a clear pattern of ovulation around CD12 or CD13 & my temps spike then start to drop about 7 DPO. They continue to drop as spotting begins then period comes about 11-12 DPO. She decided to put me on progesterone this coming month at 3DPO. Could this low progesterone be the reason for my spotting & also why I am not getting pregnant?? Also do you think progesterone could help me? My OB doesn't seem to have a lot of knowledge about fertility & my RE appointment is not till August 20th 2007.

Any thoughts I would appreciate it.