Multiple positive hpt over the course of a few days, negative test at doctors office?

I've taken multiple hpt, all of them were positive (different brands, digital tests & regular tests). I am 2 weeks late, and have some pregnancy symptoms. I am TTC and since we got those BFP's we've been thrilled. However, when I went to my doctors office and took a urine test, it was negative. Could it be that I took the test at the doctors close to my bed time and had chugged 2 water bottles prior to the test? The next day I took another 2 pregnancy tests at home and they were both positive. I went back to the doctors, again near my bedtime and it was another negative. The doctor did mention it could be because I have been using first morning urine for the hpt's, and I might be too early in the pregnancy to have high enough levels throughout the day. This brings us to today, I took yet another hpt, and this time it was negative. It was again, after drinking a lot of water. I'm so worried about having a chemical pregnancy, I haven't had any bleeding though. Is there a chance that I still could be pregnant? I really need some hope right now. Thanks in advance.