Negative HCG but pregnant?

Okay ladies, have any of you ever been pregnant but could not get a positive HCG test? I had a miscarriage when I was 18, estimated 4 months and 20 negative tests, and I'm afraid I may be experiencing the same thing right now. Iv taken multiple tests all negative except for one blue dye which I know usually isn't reliable. I'm only a day late but for the last week I have been extremely sick, light cramping, tired more than normal, food aversions, sensitive to smell, taste is off, peeing more than normal, sore boobs and extremely moody and irritable. I know these are all PMS symptoms too but my body just feels off. I'm starting to get depressed and emotional because all I want is a BFP, why is that so much to ask for ?