I'm sorry you are going through this. We see so many women on this site (and in our lives) who spend a fortune on home pregnancy tests that promise early results, and they get a whole lot of false readings both positive and negative. You started bleeding right on schedule so it's hard to know if it's your period and the HCG levels were misleading, or if it's what you fear (that you were briefly pregnant).
As hard as it is to wait - I think it's really easier emotionally to wait until a period is actually missed, and even then to give it at least 1-2 weeks. (I know that sounds like "the old days" but it makes a lot of sense in many respects.) The emotional roller coaster is so much harder than the waiting. Have a talk with your doctor before you go in for a whole bunch of repeat tests, and decide what makes the most sense financially, emotionally and medically.