Just eat. Stop acting all healthy. Eat what you want and lots of it. Don't worry how much protein is in it you can make that up with shakes. I have two shakes a day and just eat carbs all day it works and it's easy calories if i don't feel i've eaten enough in the day i feast with easy calories in the evening. Make eating your life style if you want gains. Eat one meal while planning the next
I'll second (or third?) this one. Gaining weight isn't hard. I've put on 30-40 pounds over summer break form school. You just have to go on the see-food diet... see food and eat it. Weather its milk, beer, peanut butter cups, bread, small children.... just eat. It will suck, you will have to force feed yourself, but eventually you will be able to eat more and more food and it will be a walk in the park.