Need advice/support with weight gain :(

Just a little background context for my current situation, I've been fighting anorexia Nervosa for the past 7 years and have only ever fully weight restored once (early 2013) and since then I've been in a consistent restrictive pattern with my diet and have for the past 5 years been at a B.M.I range of 13-15. I'm a male, 5ft 7, 43kg and 21 years old. I'm currently with an outpatient team/psychologist and having a meeting with an occupational therapist nurse who keeps track of my weight weekly to see if I'm making any progress and frequent blood work with my GP, I'm recently really struggling with my approach into gaining weight. (since I'm trying to achieve a healthy body weight while minimizing the amount of fat I gain during the process) I've been looking into the idea of slowly adding in calories and approaching recovery with the reverse dieting plan that I've seen layne Norton use with his clients, but I'm curious whether or not those plans are relevant to me in my current condition, since doctors want me at a healthy weight ASAP to counter the risks of organ failure and any risks of heart failure. I'm more than willing to focus on my recovery but I'm trying to not let my orthorexia determine my choices and rituals around eating, I'm currently eating 1000 calories a day while following Intermittent Fasting and eating only 2 hours a day, usually before bed because hunger at night gives me bad insomnia. I'm also walking for my only form of activity (roughly 6-8 miles a day) Since I'm at home and we have no transport to get around and any store is really far too get to by foot, and public transport is rarely available. I've been told numerous amount of times to ditch reverse dieting and jump up to 2500-3000 calories due to my activity and eat things such as Lasagna, Ice cream and lots of protein and diary foods to help with my bone density and muscle re-growth. I have also been told to ditch my healthy eating habits and take supplements followed by high caloric dense foods. I'm so confused by everything and just want some advice on how I should approach the weight gain and exercise? Resistance training is limited to home workouts with dumb bells and calisthenics. HUGE THANKS FOR YOUR TIME!