healthcare proxy? what do you do when..?

I don't have a healthcare proxy.. I don't think you have to be old and crippled to have one I mean everyone should have one..but it just hit me that me and my mom aren't close and this lady knows nothing about me, we can never see eye to eye and although I try this lady always finds a way to stress me out even more.. I do have a boyfriend but he isn't my husband (yet) .. my father is non existent in my life.. so I'm just here like okay... my sister is close to me but she's only 14 ... what would you guys do? When I think about it.. it sucks..