You have to assert yourself. If you dont start at age 18, then when?

My parents were similar, tried to control me too much. The reality was that no-one had my interests at heart more than I did... I told them this, and then I moved out of their home when I turned 17, supported myself through high school and got a full-ride scholarship to college. I graduated, got a full-ride to a PhD program. This was all without their involvement or advice. Somewhere along the way they began to believe me when I said "mom, dad, I love you guys, but Im going to do what I want, when I want. I'll try not to screw up too bad, but im doing that for myself, not for you"

Now when we talk, we talk as equals.

You need to earn their respect, this is done through actions and demonstration of responsibility.