A good rule of thumb for feeding is 1 cup of food per 30 pounds of ideal body weight for the dog. So if his 'perfect' weight is 10 pounds, he should be getting about 1/3 - 1/2 of a cup of food PER DAY...not per feeding. That adds up to about 275KCal per day for a 15 pound dog.
That means if you're doing timed feedings it's about 1/4 cup in the morning and the same in the evening. Adding the cottage cheese is fine but I'd add a teaspoon instead of a tablespoon.
As for treats...no more than one or two per day. Think of treats as McDonald's...you wouldn't eat Chicken McNuggets constantly because they're not good for you..same goes for dogs and treats.
I hope this helps.