Little Molly

This is the only dress we see Molly wear as a little girl. She wears it to the Towers, where she is left behind by the Miss Brownings.

It has a slightly raised waist and a gathered bodice:

It is made of a sheer, striped white fabric. I don't know what kind of fabric it is though.

A close-up view of the neck trimming:

Note the tie at the base of the bodice. It seemed that the back barely touches, and is fastened by a drawstring around the bottom (and probably the top?).

Are those tucks at the bottom or trimming on the fabric itself?

I think you can probably make a dress like this using Sense and Sensibility's Girl's Regency Dress Pattern, with some alterations. (Scroll down to "Appendix: Creating a 'Drawstring' Gathered Dress.") Unfortunately, I have no idea what kind of material to recommend!