Hcg levels

I had faint positives five days before my missed period my period was due may 11,2017 on may 11/2017 I took a test came back dark positive I asked to get levels checked because last year I had a miscarriage my first hcg check was 63 ,the next day 93 and three days after that 347 is this normal? I had an ultrasound and docs didn't see anything could it be that I'm to early but hcg levels are rising