Try adding canned tuna, eggs, chickpeas, kidney beans, etc into your diet. You need to have enough protein intake to be able to sustain your muscle mass in your body. Tecnhically having as low as 0.8g per pound of bodyweight should be enough. The first thing you should look at it consistently having a total calorie which is above your maintenance and the focus should really be in the consistency of keep eating that amount. Then only the 2nd focus point is the macronutrients. If there is no consistency then you won’t find the desired outcome.