I'm sorry, girly :( -hugs-
I know how you feel. I couldn't take lessons (even once a week, for christ's sake!) even if it were 10 mins from the house until I could drive and I had a job to pay for them myself. Even when I was 16, there were still opportunities that I could not accept because I was not 18 and my mom wouldn't let me travel by myself.
I hate to be negative, but really I can't blame your dad. That is a long time to drive and a lot of gas. If he works, or does anything, even 3 days a week is almost impossible. It would be time-consuming and inconvenient for him. It would be more reasonable if it were a job and you could pay him x amount of money each week for gas, but you're not getting any money.
Most people don't understand true passion for something, especially the non-horse person to the horse person. I always told my mom: "I have so much raw passion an potential, but no one to form it into something." I felt like I was wasting what natural talent I did have. It sucks! But you can only work with what you already have.
Why don't you tell that barn that you would love to commit to them, but you can't at this point? Tell them you will have your liscence in a few months and you can do it then. As impossible as it may seem, there WILL be another opportunity. When I was 16, I REALLY wanted to do a summer internship with this awesome barn, but I couldn't until I was 17. I waited a year, then FINALLy I could do it. I called them back, and they said they had a spot, just for me :)
This is really jumbled and filled with random rantings, but hopefully you got something out of it :)
Every great dream begins with a dreamer. Always remember, you have within you the strength, the patience, and the passion to reach for the stars to change the world. ~Harriet Tubman