I reckon your weight will level off when your body finds its equilibrium between what you’re eating and the amount of physical activity you do. You don’t sound underweight (no way am I commenting on your female family members!) so don’t be surprised if you lose more.
I lost a bit of weight when I stopped eating meat, but since then I’ve probably drunk less, exercised more and made other lifestyle changes over a fairly long period of time so wouldn’t attribute too much weight loss to being vegetarian. Depends where you’re starting from.
I don’t like pretend-meat products like Quorn, always suspect these things are full of salt. In our house we cook everything from scratch (takes up a lot of time, but reckon it’s worth it) and eat plenty of eggs, dairy, whole grain carbs, spinach, brassicas, tomatoes, stuff like that. Once you get into the swing of cooking using just carbs, vegetables and some dairy it just becomes what you do. For instance, bolognese sauce in our house means olive oil, garlic, tomatoes, peppers, carrots, mushrooms, herbs and spinach, cooked in a pot, attacked with a hand held blender.