Nothing in first scan..HELP!!

Ishi
Hi..  My LMP - 5 may.. Have irregular periods but this time got a second line not as dark as control
Line on 18 june and 19 june.
I went to doc yest fr my first scan n doc dint see any sac in ultrasound. He call me again after 2 weeks as he said i am in my earlypregnancy And coz of that cud't see anything.
Since my last lmp was 5th may .. I should be in 7th week pregnency .. So heartbeat should have developed ideally. Does late ovolution may be the cause .. Has anyone experienced the same and after two weeks you could hear the heartbeat .. And everything was ok?