I'm trying to conceive. i've had a shorter and lighter period. i got a false positive yesterday tested again today, negative. could i pregnant though?

Yes: There is no way of knowing whether it was the positive or the negative pregnancy that was false. Your doctor can do a quantitative HCG to help clarify this or you could repeat the test in 3-5 days. Good luck.

Need confirmation: If one test says yes and another says no then it is hard to know which is correct. In these cases blood BHCG testing is needed to confirm