I suggest too stadium at first chance. Nowadays even YA3 is not good enough to produce lot of money from selling youth as most of richer teams have it already. Most of them will go to bank anyway.
And your youth management has been quite awful (it's very common mistake by many struggling teams). You have them too much and you can't give them 20 needed matches per season. Sell those who have been 3-4 seasons with less than 10 matches- they will never be worth anything. You can play 13 players at same time and some reserve of rotation. Maybe couple of best youngsters can play in first team. With balanced youth management they will be better and more worth on market. And you can always change player's position in young age whatever their original position show.
Most of your youth are with market values 4-5M only. Higher youth academy will not help anything if you treat them same way but from well-growed players is not problem to earn tens of millions additionally every season. Fastest way to get on track is maybe: pick and save u21 league lineup from 13 youngest players. Other players who are too bad for first team sell all. Then add new pulls to rotation replacing some more wasted ones from original 13.