Generally to gain weight, you need more of everything, more meat, milk , starches, fruits and vegetables. Temper all this with some added fats, oils and sweets. You can use the Food Guide Pyramid as a guide to the number of servings. The basic guide contains 2000 - 2500 calories. You might also want to include 2 or 3 snacks between meals since you will probably feel full after larger meals.
Stress causes some persons to lose, others to gain.
Next stressor comes along, exercise regularly. I am stuck in my weight gaining. I do very little cardio exercise , but I consider myself active. Thanks for any help you can give. This was based on activities you listed.