You do not need to gain weight unless you want to build muscle for an athletic competition or sport. Is your goal to increase your muscle size for better muscle definition?
Your weight is appropriate for your height without gaining any more pounds. If you are unsure what you should weight, try my Healthy Body Calculator® and I would suggest you select maintain weight.
You can change your body composition to reduce body fat and increase muscle without gaining weight through aerobic exercise and weight lifting. If your concern to gain weight is related to your desire to increase muscle size, muscles increase with increased work unless there is insufficient food to maintain the current weight.
Food alone could cause weight gain, but the increase could be mostly bodyfat without the exercise component. Keep exercising (about 30 minutes per day 5 times per week) and your muscle size should increase if you are alternately increasing reps then increasing weight lifted. Weight lifting is effective in increasing muscle size. Have you ever worked with a certified trainer to learn how to lift weights correctly to achieve your goal?
Also, rather than trying every new fad diet that comes along, stick with the basics. Eat 3 meals per day that include 2 to 3 meat servings, 2 to 3 milk servings, 6 to 11 whole grain servings, 2 to 4 fruit, 3 to 5 vegetable servings. Limit your intake of fats and oils (8 teaspoons per day) and limit sweets (up to 1 per day or as little as 1 per week). With the My Plate plan, you will be getting the nutrients you need for maintenance and repair of your body. Also, this basic eating plan would support your athletic lifestyle much better. If you would like a personalized eating plan, try my HELP Healthy Eating for Life Plan®. You can select the type of milk, meat or not, beans or not, snacks or not. If you follow this eating plan, you should maintain your weight while exercising to increase muscle size if that is your goal.
P.S. The protein powders were originally developed for massively obese people and were to be used only under a doctor’s care. Also, they require you to increase your water intake as the protein powders stress the kidneys. Yogurt is not a magic food. Plain yogurt is the same as 1 cup of 2% milk. Fruited yogurt is the same as eating 1 cup of 2% milk and 2 servings of fruit.