A year ago I had a positive pregnancy test then they did blood work and said the number was very low, 2 days later the number was 0 so they said I might have been pregnant at that time but it did not work out. I know it is hard to see positive and than not be pregnant.
It was probably a chemical pregnancy basically a miscarriage but it cannot be defined that way If a heartbeat was never detected (too early for HB). I'm sure it was devastating for you but you did nothing wrong. I'm sorry you had to go through that hopefully next cycle you will get a sticky BFP!
It could of been a very early m/c. But in the end, you will really never know the truth because it happend so fast and there was no further testing done. I'm sorry to hear about your first m/c.
Also are you taking anything for your PCOS?
It sounds like something called a chemical pregnancy. This is where a hpt shows positive but then either your period arrives or subsequent tests come out negative.