Am I having a miscarriage???

So, 3 weeks ago we found out we were having a baby. After already having 1 miscarriage I was a little skeptic, but much more excited. A week goes by and baby is doing well. Then one morning woke up bleeding. Ran to the Dr. office where I had an ultrasound and blood work done. Nothing in the ultrasound except for a thick lining on my uterus and a cyst, which is normal. My hCg levels were 734. Tested two days later and they only went up to 846. I have now been lightly bleeding with no blood clots and cramps for a week. sometimes the cramps hurt and sometimes not. Is this a miscarriage or not??? Please help