All those people that laughed already forgot about you and moved on a few seconds after that moment. Don't get hung up on other people's judgments, they don't actually matter when you realize you only get one life and you're letting others ruin it for you. You're not gonna get younger - do what gives you meaning and you'll find fulfillment. Pursue the dreams you mentioned here because they are admirable. The people who's lives you'll be changing won't give a damn whether or not you stutter.