I'm not at all an expert, but... The bidding looks fine up until 3N. I'm not sure why you bid 4N. You know partner has under 20 points and your 11 are therefore not going to put you into slam territory. And, given that partner has only 1 point less than the maximum he has shown you, when you raise from 3N he would seem entitled to think that your hand will give him enough points for the slam.