Never been through this

TTC#3 since February 2013. No issues at all with my first two, I was pregnant within 2 cycles of trying. Last Monday, got BFP with two different tests, AF was due Tuesday. Did a blood test Wednesday because my progesterone had been low and HCG was 37 but I was told I was barely 4 weeks so no worries. Went back Friday and HCG was 25. Nurse told me doctor thinks it was a false positive and they will call me Monday to schedule an appointment. The thing is, I have all of the pregnancy symptoms. Is this what is known as a chemical pregnancy? This waiting is killing me and I just want to know what is going on. Anyone have any experience they would share with me?