I went for my 1st ultrasound today, am measuring just over 5 weeks, yolk sac was visible but no feotus/heartbeat, shud i worry?

Any symptoms?: At this early point in pregnancy not seeing the embryo or heartbeat is not unusual. Be sure to followup with your ob.

Probably not: If your dates were consistent with a 5-6 week pregnancy i wouldn't be worried. A yolk sac is about all that can be seen at 5 weeks. Assuming things are normal, there should be a fetal heart and fetal pole easily visible in less than 2 weeks. Good luck.