"If you have to ask," yadda yadda.
First of all, your boyfriend sounds odd to me-- having traditional gender rolls when he's such a bitch.
Secondly, I have never ever, ever, ever, ever known a 15-year-old girl to make a good decision on who she dated. The fact that you started dating at 15 and are 20 now, and from your description of the things he does, you should definitely look for something else.
My best friend is actually very very similar to your boyfriend. Very traditional, etc etc. His girlfriend (who was, gasp, 15 when they started dating) started having similar uncertainties much like you are. He snapped at her, belittled her (only he never realized he was doing it), etc. She often came to me asking what I thought.
After a while, I realize his behavios was "building up." It would spill over to me-- he'd treat me like he treated her. Snapping every now and then, CONSTANTLY belittling anything I said, always believing he was right, etc etc. I started to realize how she felt. And it constantly, constantly, built up. I got to a point where I downright resented him and could only imagine how his gf felt. There would be point where I would be nowhere near him, hadn't even talked to him recently, and I would just get angry at him.
He's been my best friend for 20 years, so time has little to do with it. If anything, it'll get worse. Once she broke up with him, he returned to normal and became far less insufferable. It's something akin to a power trip, but not quite.
At any rate, he's with someone who much more closely matches his type now, and none of those qualities have resurfaced yet. Mostly because they are "equals" now.
What I'd say is that he doesn't see you as equal in his eyes, and that is never okay.
My advice: Leave him and see what other great guys are out there.
My creepy advice: Dump him and come find me, cuz holy hell you are the gorgeous-est girl ever.