Have you looked into a small specialty sports gym? My son has been going to one for years that is something like $350-400/month for unlimited workouts with trainers. There are always enough trainers there to have a 3/1 ratio and every workout is custom built each day. They also work in group speed and agility days if you want it. The monthly fee also includes one add-on (1 session/month with mental sports coach, nutrition package of nutrition plan and 1 smoothie a day, synaptic training). There are a lot of places like this. Cressey is probably one of the biggest names you'll see.
Up until last year he was only making slight gains in strength and weight. I was fine with it because he enjoyed it and was building a good habit of physical fitness. Last fall he committed to eating and put on 40lbs in 4 months. He was also 5'8" going into HS and was 6'1" at the end of last summer. Clearly a late bloomer.