Is it possible to have low progesterone level even if on suppositories(m/c mentioned)

I am sorry for so many questions today. I am still trying to understand more about my miscarriage.

When I found out I was preg my P4 is 13. The doctor put me on progesterone.
I was on suppository (crinone 8%) for 3 days. My next P4 was only 8. Is it because my body is miscarrying? However, I can't understand why my P4 level is so low when I use one suppository a day.

Do you have some numbers to share? what is a normal progesterone level when one is on P4 support? Does my number show that I need multiple doses/a different type of P4?

Thanks in advance!!!