Ovulation pred kit came + on 29nov. concieved that day. today on jan4 abdom u/s says only 6w2d preg and can see only ges sac no baby.is it normal?

OPK Kit/ conception?: Ovulation prediction kits only determine the presence of LH, the hormone which causes ovulation. Actual conception can occur 2-3 days later, since sperm and egg can live prior to actual fertilization for 2-3 days. Your U/S may only see a sac at this point, so get a repeat U/S in about 10-12 days. The fetal heart should be present at that time.