Well, the big risk is if you are having an ectopic pregnancy. But then it matters how far you are along. If you are not more than 4-5 weeks along, it is not a problem and 2 weeks won't complicate things for you. If you are more than 10-12 weeks along, you should already have had problems, and thus are likely not having an ectopic pregnancy.

If you are less than 8-10 weeks along, it might just be that they couldn't find the sack at that time. Was this an abdominal or vaginal ultrasound? Vaginal ultrasound gives much better resolution and detail.

Sounds like you've had a miscarriage. If it was ectopic you'd know it...It's painful. You could let the miscarriage take it's course - the body will rid itself of the products of conception - or you could have a d&c. You could check into your state medical assistance plan - i'm not sure where you live, but where I live they will cover you to have the d&c if you qualify for ma. Good luck!