still getting postives after miscarriage??

I went to the er with bleeding and they told me I had to wait and see if I had a miscarriage I passed a colt later but no tissue and my bleeding basically stopped about three hrs after I got home I had very light stopping for a couple of days after that but its been almost three weeks since then and I'm still getting positive pregnancy tests there aren't second guessing ones either but they are lighter then my first really dark one is this normal or is there a chance I'm still pregnant I forgot to say when I was at the er I was six weeks and three day they did an ultrasound and said they could see a sack but no embryo pole but said my blood work said my levels were high