A weight would be helpful, but how much of a bulge does one pinkie make?
If you are feeding one pinkie weekly right now, and the bulge is gone in 24-48 hours, but noticeable after she eats, you are probably fine.
It's hard to starve a small corn, even if the pinkies are a little small, feeding weekly.
Weighing isn't a bad idea anyway as it will give you an idea of growth rate as well.