You are every bit of normal bro, I've stuttered on the letter F for 3 solid minutes inside of a classroom teaching students years ago, that's life, don't let it kill you, yeah, your dad freaked out, he can't reconcile your disability with how he wants you to be, thats his problem, relax, no need to be stuck in your head, I want you to do something, laugh through your stutter and give yourself a pause for as long as you need to say the word.