Hot cereals (and don't limit yourself to oatmeal) can be made with water or non-dairy "milk" (like almond milk, coconut milk, etc.). Leftovers from dinner make great breakfasts; various kinds of meats (beef, chicken, etc.) work for the first meal of the day. Lunches can easily be things like sandwiches (PB2 is only one idea) and/or wraps (lots of veggie and/or tofu options, with or without meat) or burritos made from healthy tortillas filled with healthy beans and/or veggies and/or meats. WW works for vegetarians and for people following a vegan diet; you shouldn't have problems.