Hi Helen,
The first mistake people make in regard to weight loss and leaning out is counting calories as opposed to keeping track of your macros. Macro-nutrients are nutrients measured in grams (fat, protein, carbs, fiber, sugar, etc). The reason why counting calories is not ideal is because different types of calories have different effects on your weight loss goals. For example you could take in 500 calories of pure fat (45g fat=500calories) and it would go straight to fat. You could take it 500 calories of carbs (125g carbs=500 calories) and it would restore you muscles' glycogen levels and the remaining carbs would be stored as fat. You take in 500 calories of protein (125g of protein=500calories) and it would either go to muscle maintenance or you would excrete it out in the toilet. Protein CAN'T go to fat. This is why counting your macros per meal is a lot more effective in losing weight than just counting calories.
Being that protein cannot go to fat, an effective way to lean out is to up your lean protein intake through your diet, cut down on fats, and eat a moderate healthy level of good carbs (oats, sweet potatoes, brown rice, etc). Being vegan does make it more difficult to tailor your macros to high protein without the excess carbs. Your best vegan protein food options are black beans, split peas, and lentils. They still have a 1:2 or 1:3 Protein to Carbs ratio. You need a protein supplement to really help tailor your macros in the direction of more lean vegan protein without the carbs. I would suggest Real Pro Life Nutrition's plant protein. It has the industry's highest gram for gram protein concentration. The fake meats are also good (Beyond Meat is my favorite). However you really have to look at the nutrition facts to see the fat content. Some of them have a lot of fat in comparison to protein.
The lesson here: count your macros, not calories. Always look at the nutrition facts and do the math. If you have any questions hit me up, I am happy to help. Good luck Helen!