Calories and protein

Nutrition is hard 🫠 So I'm on a weight-loss journey. For context i weight 285 lbs and I'm a 5'1 female. Ive lost 35 lbs so far but I keep losing muscle when I lose weight. My doctor wants me to only eat 1200 calories but also wants me to consume 120 g of protein at least and only 30 g of fat. I'm really struggling to find a way to consume this much protein on such a strict diet. Any advice? If I hit my protein requirement I go over my calories. If I'm good on calories I dont eat enough protein 😕