I'm having a hard time...maturing into a responsible and alert adult.?

My birthday is tomorrow (April Fools Day) and I'll be turning 18. Funny thing is, I don't feel quite 18, but actually like 15 or 13. Why? My dad always gets on my case for not being responsible, alert and smart enough and tells me I'll be a future loser if I keep it up. I mean, he's never let me out of the house ONCE without some sort of supervision, he wouldn't even let me go off by myself to do something when I was little. I've always lived my life with my eyes covered, blind, with someone dragging me by the hand.. and now he automatically expects me to be responsible when I've never had a damn thing to take care of? What will I be? I feel like such a loser when he lectures me about HIS life and how hard HE had it.. but WE are VERY different. I'm also an aspiring artist who wants to work for a toon company or advertising and publishing. But no, he tells me to be a nurse instead. And it leaves me in the dark... looking out to nothingness.. wondering, when will I finally mature?