my 1st scan i thought i was abou 8weeks & they didnt see nothing but a sac, went again 2 my ob and they did another u/s a few days later, and still didnt see anything.. 2 make a long story short i was nt as fas as i thought i was.. They finally seen something when i was 5w6d.. And now im 18w4d and the baby is fine.. So try not to worry:)
it's possible that you ovulated later then you thought and that could be why he didn't see anything...... I also have an introverted uterus and that made it hard for them to find the heartbeat using the Doppler ( took til after 15 weeks ) ..
I would try not to worry I have seen lots of people post that the doctors didn't see anything and then a week or two later there was their healthy baby :)
I will keep my fingers crossed for you