21 weeks with twins and not showing much?

Ashley
Hi all: I am 21 weeks pregnant today with ID twin girls and I am barely showing. My doc says the girls are great and everything is fine but it's so odd. This is my first pregnancy and I am tall (5'8) with a long torso but is this normal? I also have an anterior placenta and can't feel much movement but slight flutters! #nervoustwinmama