Sounds like your boss is doing you over there, however none of us know how you perform, for all we know you might only be worth 70-90 per day.
When i was 19 i only got ÂŁ132 per week, i had a van supplied and was carrying out jobs of my own accord, but i knew my place, i knew i wasn't qualified and one day would be all worth it so grafted on which has got me where i am today
The moral of the story is don't expect the big bucks all at once it comes with time and hard graft, and don't be afraid to speak up for your self if you think your being buggered, this is how these people get away with it because too many people now are too afraid to say anything.
PS why have you not got your driving license at 19?