6 week 2 day scan but no baby.

Hello last Thursday I went for a scan as had cramping and I was 6 weeks 2 days and they saw a sac but no baby. Could it be that it's just to early? I'm going in for a scan on Thursday which will be excatly a week. Did this happen to anyone and then they saw there baby at 7weeks? It feels like forever waiting. Appreciate any type of response good or bad.