Assuming you dont have body fat issues I would increase your calories through ‘good’ food such as more meat, veg and good carbs. Also I would invest in some meal replacement shakes, it sounds like you have a busy schedule and these provide a good meal for people on the go. Also in terms of workouts 2 strength sessions per week should be enough to maintain your muscle mass. These could last 30mins and just be packed with core lifts, I suggest browsing Ash’s sample programmes and picking out 30mins worth of lifting. You could split in terms of 1 full body workout with a push/pull superset on the end and then an upper body workout. Be aware that if your game is not that demanding there is nothing wrong with a doing a high rep 30min blast the following day, this can even help with recovery.