In my case is the exact opposite, I stutter way more in my native Spanish than in English, and I've seen this pattern many times of people stuttering more ir their native tongue than in other tongues. But clearly it can be the other way around as in your case. I don't think there is any technique to get rid of stuttering in any language, but being confident will sure help you. Lack of confidence and nervousness makes stuttering worse regarding the tongue.