At professional level you would still be considered a boy. Professionals get better with age due to strength and experience.
Obviously playing at a lower level comes down to your lifestyle. If your currently going out on the p*ss every weekend then your best days are in front of you. Or if you start going down the pub most weeknights nights to get away from the missus in a few years time then you'll never be able to hit the ability level your at now.
fwiw I'm 31,my best years were probably 24-28 but I haven't seen a massive amount of change. I'm still chucking myself in the air and doing overhead kicks and s*** which is what I was doing when I was 18
My problem is I smoke,and that naturally has had the biggest impact on my fitness over time.Technical ability though hasn't really changed. It's only now in the last couple of years it's making me realise I'm getting on a bit
But for a 22 year old Pro,this really is the time they need to start getting regular first team football if they're ever going to have a solid career.