No, it's not a problem. Don't worry, it's good if you never need it.
Im measuring 2 weeks ahead but Im not sure if that would be considered a problem. I just thought they did it to everyone but baby has been healthy all along no problems.
They do nst's at labor and delivery each time you go (if you've been for anything post first trimester).
Not all doctors do one unless there is a reason for.it.to be done
If you aren't having problems you usually don't get one. It's just where they put the straps and fetal monitor around your tummy to check baby's heart rate and to see if you're contracting.