Sounds to me like all you need is some consistency.

Make up a meal plan that you can follow every day with enough calories to start gaining weight slowly (I'd estimate between 3000-3500 for you). Keep using the types of foods you have listed there. Keep your protein high.

Start going to the gym consistently 3x or 4x a week. You should also have a training routine. Your routine is pretty sh!tty, I'm not going to lie. Look around here for routines for beginners.

You need to start trying to do squats and hopefully deads. Start as light as you need to... bodyweight if necessary. You can do lunges so squats can't be that far off. Be as strict as possible with your form. (which assumes the fact that you should KNOW HOW TO SQUAT/DEADLIFT properly to begin with ... if not, get a reputable trainer to teach you.) Squats and deads will be the key to your weight gain.

Those are my tips. Take it or leave it.

IW