Eating high calorie foods will help you gain weight. If you want healthy food, you can do that too. You can have grilled chicken, soy burgers, fruits and vegetables, or oatmeal and other cereals. There is alot of tasty food you could be eating, if you don't like the shakes.

Follow this meal plan 7 Carb exchanges, 6 meat exchanges, 3 dairy, 5 fat, 2 veg and 2 fruit. 1oz of meat is 1 protein exchange and 1 sl of bread is 1 carb exchange. You can look up food exchanges online that will go more in depth. I understand you situation i am also 15 and recovering although i was never that low i went from 93 to 98 in 4 weeks and now that my body is at a normal weight my metabolism has restored so i can now exercise try it. I go to a rehab center and this is the diet i was on.

20 yrs recovery here and AGREE 100% with meal plan above/exchanges. Give your body/metabolism time to adjust (easily 1 yr) Increase proteins and keep "nibble cup" filled with your fav. snack (I love trail mix) and eat at least two cups daily. While in weight-gain mode do not count this as exchange but do journal it. Also, I was taught NOT to count fat, weigh measure food but keep strict food journal (easy as healthy compulsive exercise ha!). A serving size is equivalent to Picadilly/cafeteria serving. Write down mayo, heavy cream, oils but don't count. My nutritionist counted a candy bar as 2 starches & 1 fruit. Over time the way you feel and your clothes fit (not number on scale) will let you know if you need to adjust fats and the way you monitor them. Best of luck. You can do this!! Not a professional just a survivor so run ALL by you Dr.