Probably only way to fix stuttering(for me)

Probably only way to fix stuttering(for me) I had speech therapy when I was 8. At that age, I didn't care about anything because I was just playing Roblox, so I wasn't applying this therapy. The therapy was just to breathe deeply and talk slowly (almost 0.25x speed), I am now 17 years old and will be going to university soon.I feel very strange while doing this therapy, but surprisingly it prevents my stress and stuttering. Do you think it's too late yet?