I wanna be happy, like now?

My parents are making my life miserable right now, but keep saying "if you don't listen to your parents, your life is going to be difficult". The problem is boys. I'm 16 and a half for godsakes I think I should be trusted to go out wit a guy and have my parents complete trust. They think otherwise. My cousin jus had a baby a month ago, her wedding was last weekend and my parents think her life is pretty much over cuz she has no job and isn't going to school anymore, she's 21. Anyways, I'm into her husbands lil brother and I kinda wanna see how things would go. But my parents think imma make the same mistake as her. They have high hopes for me, I wanna become a surgeon and that's my plan, I know that if I got pregnant the way she did that's all over, but my parents still say no. How can I make them understand that I know that they want me to have a happy and wealthy future, but that I also wanna be happy now. I've been into boys for the past 2 years now and they don't get it. They've made my life a living hell the past year and a half because of a guy. What can I say?