Low HCG levels

Hi ladies! Has anyone experienced low levels and also low progesterone early in pregnancy? And how did it turn out? At 5 weeks I was at 41. 3 days later it went to 46. I am also taking progesterone suppositories. My doctor said hcg should be doubling. I’ve had a few chemical pregnancies and a miss at 12 weeks back in November. A few days ago I started to have a very dark brown discharge/spotting mainly when I wipe along with very mild cramping. I’m hoping it is implantation, but not exactly sure what it is. I never experienced anything like that with my successful pregnancies.

I am 36 years old and I have 2 sons. 6 years old and 21 months. First son conceived no problem. Second I had to have an hsg procedure done and within that month got pregnant and had no problems during that pregnancy. I don’t know what has changed besides my age to be having such a hard time this go around. I am getting so hopeless but I try to leave it in gods hands. ❤️