Conjugal Partnership or Spouse help

Hi i posted once before and i am now in canada on a visitors visa yet again for the third time. I am a British Ciztizen and my girlfriend is a Canadian Citizen. I cant stand to be away from my girlfriend so that is why i am back just as a visitor. As it stands we have been dating each other for about a year and a half, I have visited here 3 times now once last june for 4 months then again in september for 3 months and i just returned in february we both love each other and we are looking for something permanent. I have been reading about a conjugal partner visa but i have heard that more often that not it would get declined, although my girlfriend has been refused for a long stay in my country already which was one of the requirements. We are also considering marriage as a serious option and if we did so what are the chances this would be successful. We do have chat logs from msn messenger for the whole duration of being together we did send each other e-mails every day at work/school back and forth we have pictures of us together and with her family, we have both families blessings i have proof of tickets back and forth that i have totalled somewhere around 6 thousand dollars on just flights alone.

Another question i have is on the website the age to sponsor someone is 18, my girlfriend is still in school at 19 taking some further education so does not have any income as such but they would want proof that she could support me financially which she can not? I am living and paying rent with her sister which she is quite prepared for me to do. I could get myself maybe a lump sum but not tens of thousands which i could bring over and to be able to use to hold myself till i found a job. I have all my high school education i have an advanced a-level in biology and i have a diploma from college in environmental science. How is she supposed to be able to sponsor me financially?

Please any information would be gratefully appreciated