coralush, wrt protein/carbs, it needs to be a very gradual reduction in carbs. If you cut too much too soon, you will likely experience proper withdrawal symptoms, I.e headaches, feeling weak, cravings. Slowly, slowly, try to choose some protein over carb, e.g eggs and cheese for breakfast rather than toast. Try and avoid/reduce anything flour based, esp refined white flour. Boiled/mashed potato, swede etc is fine.
Have as much good fat as you like, it has no bearing on blood sugar/insulin.
Try to replace refined sugar foods with natural sugars like dried fruit (excellent) or normal fruit/ sweet veg eg carrots, red peppers, tomatoes.
This takes time, it is making choices towards protein, again and again. It fills you, it makes you satisfied, builds muscle, it will never make you fat even if you have a whole beef joint in one sitting (nobody can actually). Carbs, on the contrary, esp refined flour and sugar send your blood sugars haywire, which triggers excessive insulin production which tells your body to store fat even when you really don’t need anymore fat.
Only advice I will give, do it gradually, if cravings/ blood sugar crashes get too much, have a little bit, but go straight back to making better choices. It is a long game, but you will look and feel fantastic and will need to make no effort to control your weight. It is impossible to put on weight when you eat high protein/high fat and low (good) carbs.