Im on a diet with high protein to lose fat and gain muscle, my diet is 2000 calories per day and only consists of: protein shakes, milk, flaxseeds, chicken breast, broccoli, brussel sprouts, green beans, egg, pasta. am i missing any vitamins?

No. Your diet covers all of the vitamins and essential trace nutrients. You will need to exercise to gain muscle, diet alone will not do it. A combination of aerobic exercise and resistance exercising/weight training will be needed to improve your muscle mass. The amount of gain will also be determined by your genetic make-up. Wish you good health!