I would suggest you talk to a doctor that is trained in not only as a doctor of medicine but as a doctor of nutrition and dietary counseling. I had a friend that could eat more than me(and that's hard to do) but was about your size and could not hardly gain any weight no matter what she ate or how much. If your really worried about this you need to talk to the right people(doctors/dietitian).
I'm 17 Years Old And A 5'6 Feet Girl. The Problem Is That I Am Underweight And Skinny. I Am Only 47 Kg. How Can I Overcome This Problem And Gain My Weight?
I had that prob but I wasn't that skinny all I did was for about a week I just had out all week like at bk and md like take out places and that made me gain like 20 lbs and if you need anything else you can just ask me I have went threw the same thing ttyl
You have to add some carbohydrate rich food in your diet like potatoes and rice.