Hi Laura,
You need 1,400 calories just to maintain your weight at 110 pounds. In order to gain at least one pound a week you need to add 500 calories a day. Adding 500 calories a day is very very easy (IMHO)
Eat what you normally like but instead of low fat soy milk or low fat yogurts go with the full fat versions, these should be monounsaturated and polyunsaturated fats. You should be able to easily add 40-50 calories per cup.
Add peanut butter and more smart balance to gf breads, crackers, rice cakes, add real mayonnaise to sandwiches. Real mayo contains a whopping 90 calories per Tbs. Watch for preservatives and hydrogenated fats.
For an easy 200 calories a day just add 1/4 cup (palm full) of walnuts or nuts. If you like nuts, this is one of the easies ways to add calories fast. Add pine nuts, sesame seeds, sunflower seeds to vegetables, salads, soups....really anything as a topping.
Are you doing dairy? Add nuts and dried fruit to ice cream or coconut ice cream, soy yogurt...get the picture.
Dried fruit and nuts are also high in calories and easy to get in 1/2 cup at an average of 280-300 calories.
Do you like guacamole or hummus? 1/2 cup is 200 calories with great nutritional profiles. Hummus contains about 125 calories for 1/2 cup.
Look at bumping up protein a bit too. An extra egg, an extra ounce of chicken, turkey dark meat.
Good luck, how's the appetite?