I know your problem, I have had the same trouble in a L5R game where I played the courtier: the face, but much more political, where a faux pas will get you killed, or worse, shunned (and yes, that is worse). I'm not good either and the main problem was one of the other players was and he played the gruff warrior, but was always taking over.
Have a talk with your GM about it, explain why you want to roll dice in some circumstances. It should stay fun for you as well, and having constant stress isn't much fun.
In fact, when I GM, I always have my players roll dice (for the important things at least), but I also have them roleplay the situation, with good roleplay giving bonusses and if they make the big faux pas, they get a penalty (faux pas here is of course really stupid decisions, not if the player is not good at this thing).