Dear Mom and Dad.
Particularly Mom: if you keep pushing me the way you have been doing, I WILL LEAVE. It will probably make me poor, but I'd rather be poor and happy than supported and unhappy. I wish they would let me live my life, I'm the responsible adult they raised me to be but they won't treat me like one.
Same situation I'm in. My mom is a little more supportive than my dad, but still, they are pushing me to do what they want and it's horrible! I want to live my life, not theirs.
They're just trying to protect you, I'm sure. I would love to live with my parents again, instead working my ass off at the crappiest job ever just to support myself. I can't even afford food most of the time. I never have time to have fun, just working and sleeping. Don't grow up too fast.
I've come to realize that if they are treating you like a child, it's because you're acting that way towards them. You might be mature when you leave the house, but once you step in - it's whining and tantrums. Check yourself.