Do I have a chance of being 'big' in music when I'm older?

its possible, you sound totally dedicated! Just remember when you start your band dont do it to be famous make sure its all about the music, not the fame that way if you sell a record and it doesnt sell very well it wont bother you cuz you know its all about the real fans and the music. Also your band will be garunteed to stick around much longer!