I need a little guidance in my life?

I'm 18 and very soon to be 19. My whole life I've lived in fantasies. I've spent time pretending to be a high school basketball star, a star athlete, a genius writer. The list goes on. I've always strived to impress, or rather make a strong impression on a group of people who are either ignorant or doubtful of my latent talent. With highschool done, I have no immediate group of peers left to make a strong impression on. Because I'm so slow I can't keep a fast paced job and I lost my only well suited job at a call centre due to my own stupid negligence (lesson learned). I'm slowly watching myself become less of a "child with potential" and growing into a grown man who lives with his parents, has no job or drivers license. I failed my first semester of University and I'm really skeptical that I will do well. For the past few years, I've been stuck in a guitar playing fantasy. It started in high school when I was 15 I received a guitar. I immediately started fantasizing about impressing my high school peers. I became fixated on it, and I deluded myself into thinking that I would "win" and the credits would roll. I would have a "Yo Adrian, I did it!" moment. I'm still stuck in that fantasy, and I'm begin to test the patience of not only my parents and those around me, but myself. I'm self aware enough to know that I probably won't have enough success as a musician to support myself financially. This dream/fantasy, the guitar one I mean, is different. I'm playing shows, and getting infront of audience. However I can't help but feeling like a archetypical loser. I mean, no job, failing university student with some deluded rockstar dream? The crazy part is, I STILL fantasize. I get home from playing a show and I put on music and fantasize about impressing people. But not at a show... at a party with a group of peers who are ignorant and/or doubtful of my abilities! It's crazy, I've already made my shows known to people, and the girls who never paid attention in high school are curious about when the next show is. On the one hand, I'm the guy who's winning over club owners with my songs and lyrics and slowly becoming into the adult I want to be. On the other, I can't hold a job, I have terrible grades, and I'm on my way to being 26 years old and still living with my parents, and STILL fantasizing about showing that hot girl on the bus I can play a mean solo! I never wanted to be the loser guy who "still hasn't given up on the band", but I sadly feel I'm destined to become that. I'm not a "music is my life" kind of guy, in that I dont believe its all or nothing. But I feel like a bad american idol audition waiting to happen. I dont wanna play a show and have no one show up. Or have a friend or a parent say "just give it up". I dont wanna borrow money from an uncle to "buy a van" and "tour the world". I dont wanna be the guy at family reunions everyone feels sorry for. I don't want to be a failure at life, or a loser. But I fear I am headed down that road, anyone have any thoughts?