Gluten-free weight gain?

I am 5'9" at 112lbs, with a BMI of 16.5 (the ideal weight for my height is 140lbs and a healthy BMI is 18.5). I have a gluten allergy and have struggled with anorexia in the past. I'm afraid of relapsing, but I need to gain weight - I want to be healthy. I'm wondering if anyone has any tips as how to gain weight with a healthy, gluten-free diet, while maintaining a good figure.
Gluten-free weight gain?
Post Opinion