knitting a dress without a pattern

Hi everyone

I am knitting a dress without a pattern and I could use some help. It’s for my daughter. This is the link to the dress https://www.clothingi.com/products/women-elegant-round-neck-long-sweaters.
It’s a rather loose pattern, I think. How many inches positive ease should I have? My gauge is 18x24 per 3’’ which makes 6 sts per 1’’ and the actual body measurements are 35,5’’ for the bust and 38,5 for the hips.
Thank you guys in advance

Very nice looking!
It really depends on personal preference. There are patterns with 6-8” ease at the bust and 8-10” at the hips. I’ve seen up to 12” at the hips. Maybe try on a dress or even a t-shirt to see what seems reasonable to you.