I've been taking ovulation test strips, which became positive on may 8. i got a positive pregnancy test may 12. how can it be positive so soon?

Not likely: Conception, as defined by the generation of a fertilized ovum, occurs within day or so of the sex. However, it takes about two weeks for the embryo to make enough HCG to produce a positive pregnancy test. Blood test may be done a day after a missed period. Home pregnancy tests should be done 4-5 days after the missed period. Please seek care from a doctor to protect your and your baby's health.