Help please

I'm around 5 weeks pregnant and Friday I started spotting while I was at work. I went to the ER and they did an ultrasound and saw a yolk sac. They said my levels were a little low, around 450. They said I could possibly be wrong about when I conceived and not to worry. They gave me progesterone pills. 100 MG 3x a day. I'm still spotting worse than I was Friday, but it's not getting worse that yesterday. Anyone have any advice? OHHHH, and this is my 3rd pregnancy. I had 2 consecutive miscarriages at the beginning of the year.