Low hcg levels and low fetal heart rate

I found out a couple weeks ago I am pregnant. Because I had a miscarriage last Oct they had me go for blood work 2 weeks in a row. My hcg levels are going up but not as fast as they should. Also last week I had an ultrasound and baby had a heart beat but it was only 115bpm… I go back on Friday for another ultrasound… I am Wondering if anyone else had this kind of experience and had a healthy pregnancy.