Is my HCG high enough?

I am estimated at just beginning my 4th week and my HGC level came back at 51. They said it was consistent with as early as I was. I am going back on Monday for a second blood draw to make sure they are doubling.

I had an eptopic miscarriage last year around this time and I am terrified.

They put me on Progesterone supplements just in case my progesterone levels were low, but my test came back saying they were at 18.7 before starting the supplement, which they said were great, but I am going to continue taking them because I was spotting brown at my appointment, which they said was normal, but better safe than sorry.

I just want to know if others have started there and had a healthy pregnancy.

The last time I had one was my daughter 11 years ago, and I didn't do any of this that I remember, but I was just 20, and not high risk.