Ttc. lmp 3/2/13. positive opk 3/17. light positive hpt yesterday but then negative blood test. still no bleeding at all. what's going on?

Hard to tell: It is best to get sequential beta HCG levels (the pregnancy hormone) via blood testing. In most normal pregnancies, the beta HCG will double every three days. Miscarriages occur relatively frequently (about 20% of all recognized pregnancies). A beta which goes up and then comes down may be a sign of a pregnancy that is not destined to continue. See your ob. Good luck !