My little Tsubi is 2.5lb at 1 year and She is the biggest eater out of all my 3 girls but she won't gain an ounce even..sigh..

I got all the testing done on her and she is super healthy and there is nothing wrong with her. It just that she is super active and doesn't sit still..lol..The vet said she is just really active and has fast metabolism. I wish I have that!! I am feeding her all through out the day but still no weight gain. i want her to be at least 3.5lb..I just need her to gain a lb..is that too much to ask?hahah..