What Does Ultrasound Scan Result Showing Only Presence Of Gestational Sac Indicate?

Had a scan last night showed 8mm gestational dac but nothing else unsure on dates as was on pill with no periods and conceived straight away from stopping pill. A digital preg test showed 4-5 weeks a week ago so assuming I m 5-6 weeks now. Is there a chance everything will still be ok or do u think I m miscarry ing?