G sac seen in U/S

saniya
I just got my ultrasound done this 27 September, it showed clear gestational sac and Dr. said I am 5 weeks pregnant. So here is the confusion, I got my periods this month also on 15th. Could it be possible to be pregnant and having periods too, the Dr. suggested beta hcg after two weeks. Also I am not facing any pregnancy symptoms yet. So confused.. can't wait.. need your opinions asap