ano toki kara
sukoshi mo
seichou shichainai あの時から
少しも
成長しちゃいない
[I] haven't matured even a little since that time.
I.e. Edward did something stupid before, and he feels he didn't learn anything since that time, he hasn't matured, grown up, improved, etc. Nothing changed, and he's doomed to repeat the same mistakes he did in the past. He implies he's an idiot because he hasn't learned from his past mistakes.
