If you want to gain weight you've got to eat more. I know, you think you're eating constantly. You aren't. Get more protein, get a bunch of carbs immediately post-workout. Start lifting. Sorry but pushups, situps, and pullups together is not a workout. Lift heavy things, squat, eat more, gain weight.
With the milk, I would say suck it up and drink it anyway. I find olive oil shots revolting but they help.