angelbrat, I just gave you a positive karma.
To the original poster: Sweetie, things will not work as fast as you'd like them to. First of all, you can come to Canada and visit after your 18th birthday, and you and your fiance can get married here. Although you will probably need your parents permission as the age of majority in BC is 19. Do not plan to bring a lot of stuff with you, if the Immigration officials think you are trying to move here, they can deny you entry to Canada. As an American, you do not have the right to come live in Canada, and even visiting can be a privilege. You will not be able to work while you are visiting.
Then you can apply outland for spousal sponsorship so you can become a Permanent Resident. You can stay and visit while the application is in progress, but you must apply to extend your visit if your PR has not come through by the end of your 6 months. You may have a more difficult time being aproved quickly because of your age. You will likely have to have an interview in Buffalo. How old is your fiance?
During this time you will have NO MEDICAL COVERAGE. Medical care in Canada is just as expensive as it is in the US, except our government pays for it for Canadians - not visitors. Without coverge, a pregnancy and birth that has absolutely no complications will cost you a minimum of $15,000. With complications like a c-section, it could be $40,000.
You would be well advised to wait until you have Permanent Residency and are covered under BC's health plan before you consider becoming pregnant. Some provinces have a 3 month waiting period after becoming a PR.
I'm glad you still have 10 months before you are planning your move, it will give you time to really think about what you are going to do. When you and your fiance visit each other in this next year, be VERY careful that you do not get pregnant...you would likely end up having your baby in the US while your fiance is in Canada which would be terribly sad for everyone.
I'm also curious to know - what do your parents think of all this??