I am 4wks 2dys pregnant. I had an ultrasound & it says my gsd is 17mm with no fetal echo seen yet. Is this normal?

Probably not. 4 weeks 2 days pregnant essentially means that you just missed a period 2 days ago so generally on ultrasound you won't see anything. If there is truly a 17 mm sac with nothing in it at all by a vaginal scan, it is unfortunately not a good sign for a viable pregnancy. The whole story doesn't make sense, so i'd recommend that they continue to follow your lab work and ultrasound to see what happens.
Early pregnancy. At 4 weeks pregnant, it is normal to see only a gestational sac on the ultrasound and nothing else. In the next two weeks you will see the development of a yolk sac and then a fetal pole. Your ultrasound findings should correspond with your blood HCG levels - check with your doctor to make sure they do. Also call your doctor if you have any bleeding or pain.