By the way, you look great. If you want to add size, though, you need to increase your eating. At your age, it is especially difficult, because of metabolism, but also because most folks your age have no clue how to eat properly for putting on size. When I was your age there was no internet to ask about this stuff. You have an advantage, so use it.
Buy the food and cook your own meals, and do not wait on mom to do them.
Try this tomorrow.
1. 8 eggs, one cup (dry measure) oatmeal, two slices of whole grain toast, and a cup of tea or coffee.
2. 8 oz (that's half a pound) chicken breast, cup of rice, spinach
3. Repeat 2.
4. 8 oz chicken, half cup of rice, spinach
5. 8 oz chicken, spinach
6. right before bed, two cups cottage cheese with almonds.
Drink the protein shakes at workouts only.
That's two pounds of chicken and plenty of carbs in one day.
Do that tomorrow and let us know if you can get it all down. Then keep doing it every day for a month, and let us know if you put on any size. Please keep us posted.