yeah im about 220 and my cousin is about 130
You're kidding right??
Jeez, if that is truly your size difference then it really wouldn't take that much to tap him. Go roll with a blue belt that's at least close to your size and see how that turns out...
We have white belts in our class that are close to your size and they tap some of the blues that are about your cousins size with pure strength and size, no technique at all. Then when they roll with someone like me that's about 205 I smash them like they are nothing.
You need to go join a gym because tapping someone that's 100lbs. lighter than you definately does not warrant you getting a blue belt by any means.