Congratulations on your pregnancy!
The Fetal Pole is normally seen as early as 5 1/2- 6 1/2 weeks. Although, your ultrasound is giving a date of 6w, 3d-- that is just an estimate...if you know the date of your LMP, that is the most accurate date to go by. Try to remain positive, development occurs extremely fast in the beginning of pregnancy, so one week will make the world of difference.
Take good care of yourself and keep us posted,