If the simulation of your garment doesn't give you the right fit, here is a selection of tips to help you.
Review the tension and pressure maps.
Fit issues in the simulated garment can be caused by an incorrectly oriented grain line on pattern pieces. Texture maps may show a correct grain line, but not reflect the actual grain line applied on the pattern piece. So, view and check the grain line.
Consider using transparent fabric.
Don't forget the availability of rulers and the 2D Measurement tool.
Use the pen tool.