I can relate to this brother, I developed stuttering/stammering at an early age and I'm still struggling with it till this moment. I believe it started at 11 or 12 and now I'm 27. Contrary to you though, It strikes me the least when I'm praying or when I'm reciting the Quran. But it gets unbearably frustrating at times in day to day situations. Arabic is my native language though so I'm not sure if it makes a difference. Just stay strong brother and pray to Allah and he surely will help you.