need help

ok i have never been to canada but im going to canada in november 28th this year for 3 month but my girlfriend who is a canadian citizen has been to england united kingdom at the beginning of this year but we known each other for 4 years but i am confused on how to get there to stay my questions are

if i go for 6 months and got extention for another 6 months would i be able to proceed for PR card and could i stay while processing also if im there for that long do i need a sponsor as in my girlfriend but we are worried that she might not be able to sponsor me because of financial difficulties

i have severe sight problems would that affect me to get in canada i can work but theres alot of work i can not do like skilled work or driving im just really confused to what to do or if any other information i need to know to help me get to canada to be with her any help is much appreciated