I have trained for 12 years and gained 60 lbs of lean muscle naturally. Protein consumption is motly determined by your level of calories. You can gain muscle as long as you eat a lot of calories and a minimum of 0.8g per kg of bodyweight. I have tested all kinds of amounts. The minimum works. Keep starches high, fats and protein the same. Say 60/20/20 for example. Dont get hung up on numbers. Just eat wholesome unprocessed foods plus ice cream for desert. Drink half and half instead of milk. Take small steps and see how your weight increases weekly. Keep track of your waistline as well. I suggest HST(hypertrophyspecific.com) as a training routine since it has research backing its methods and its progressive.