5' 6", feminine soft/atheletic? The game always says she is strong, so I had started off at 5' 8", with a feminine/fit build like a cross country runner. Not heavy muscle definition, but reasonably built to convey strength.
You can do your best to describe, I will do my best to sculpt it. She is your character, should be done enough to make you satisfied with the result.
If you want to toss a reference for anything (face shape, body shape, heck even clothes) I'd be glad to help. I'm going to adjust the model I already started on to reflect what you've already clarified.