It’s not likely that its "too soon", but I have heard of stranger things.
One thing is the level of HcG has to rise exponentially in the first few weeks for a pregnancy to be viable. If your HcG doesn’t rise, your body will expell the pregnancy because it cannot sustaine it. Have you spoken to your doctor about your symptoms and negative tests? Since your negative blood test results? Because if the symptoms are still present you should definitley look further into it.
I also agree with the previous poster – it could very likely be a cyst or something of that nature. Either way you need to find out!