Well, vegan foods with lots of proteins include: Beans, lentils, peas, nuts, peanuts, tofu, soy.
Personal favorites are red lentils (cook pretty quickly and don’t need to be soaked before) and pre-cooked white beans (I just have a jar of those in the fridge and will scoop a spoonful into all kinds of meals).

Proteins are cool, because they stick around in your stomach for a while, but they’re bad at filling you up. For that, salads and veggies are the best. Sometimes, I’ll eat an entire bowl of salad, which is not a lot of calories, but still fills me up.

I would also recommend slowly changing your diet over. Your gut microbiota need time to adjust to a different diet. If you don’t give them that time, they can kill your will pretty effectively.