Help! Confused

So I took a ClearBlue pregnancy test and it came back positive this was a week ago. Today I visited a clinic to try and get an ultrasound && the told me my urine test came back negative. My last period was March 28th. I feel every symptom of pregnancy my boobs still hurt, I'm still cramping, etc. I'm looking for places the offer blood test. I'm just nervous that maybe I had a chemical pregnancy but I have yet to bleed at all. Help!