M.,
STOP reading everything about it! Those doomsday sites are only going to freak you out, not give you answers. Those are, most likely, worst case scenarios, and are not about your specific baby. If there was something to be concerned about, don't you think your practitioner would monitor that a little more closely rather than having you wait for 4 more weeks?
Also, it is important to ask yourself and your husband one, huge question: "If these websites are true, and our baby has serious problems, will this change how special he/she is to us? Will we love our baby less, or not at all, if he'she isn't perfect?" We have no way of knowing what God's plans are for us, only that His dream for our lives and the lives of our children are far grander than anything we could conceive of. I've had a couple of scares in 3 out of my 4 pregnancies. It's frightening, but I took huge comfort in knowing that God loves my children even more than I do, and he's taking cares of us all. Good luck, and God bless!