Is it possible to sustain a pregnancy with a progesterone level of 7.4?

I had a missed miscarriage in January and have been trying to conceive since March to no avail, I found out today that it's probably b/c my progesterone levels are low. I ovulate late and start early so I guess it's a luteal phase defect. I am wondering if there's any hope for sustaining a pregnancy at this point (CD 24, 8 DPO) with prometrium? If not, I guess I have to take the prometrium next month, 2 days after ovulation through 10 weeks assuming I do get pregnant. I am so frustrated. Is it possible the progesterone is what caused my first miscarriage, although we found out at 12 weeks and had seen a great heartbeat at 8 weeks?