Positive urine tests but negative blood tests

So I got a positive pregnancy test on Saturdsy. It was a faint positive. Then I retested yesterday and it looked negative. I called me Dr and she had me come in and do a urine test and it was positive. She ordered blood tests and it came back as negative. What the heck?! How is that even possible? What should I even be expecting? I am a week late. I've had some symptoms of pregnancy like weird cramps, dull back ache, tired, dizzy and headache, hungry, my skin is glowing, I'm peeing more than normal. I don't know what to think or do. Had this happened to anyone else? What ended up happening? Any advice?