Same Sex Couple Advise

Hi guys, I am hoping you all can give me some advice on how to go about this whole immigration thing because its pretty nervewracking just to even start thinking about it.. My partner and I have been together over 2 years now. He is Canadian and I am american we live 5 minutes away from eachother right over the Rainbow Bridge in Niagara Falls NY/ONT. He had a house last year that I basically lived in a lil more than half the year until he had to sell and move in with relatives. We are looking for a house again and I want to make sure I'm doing the right thing when it comes to the border crossing..

In the past there were a few nasty customs officers at the booth who threatened me and had me "pulled in" for living in Canada illegaly...When inside they would say just watch how much you are here and have proof of US residence and let me go.. Our biggest fear is that one night I will get an officer to ban me from Canada. The biggest thing I need clarification on is the 6 month "visitor visa" Now I know we don't need a physical paper Visa since Americans are exempt...but the question I have is.

Can I use the 6 months throughtout the year "legally" Meaning if I circle the dates on a calendar that I stay over in Canada and they equal or are less than 180.. Is that ok? I have a room at my grandparents home that I live with and is where I will be every other night when I am not in Canada. So if they wanted to argue with me, I do have a place I stay every other evening so I obviously still live in the US.. And my job is here too of course. Should I ask them for a multi entry visa paper or something to be more official?

We are eventually going to get married (previous marriage and being same sex doesn't make the decision easy, but I think that is the best and easiest way I can immigrate and we can be together in Canada. .

Any tips you guys may have would be greatly appreciated. I have been keeping records of our phone bills, emails pictures from start of relationship going forward...It's just the fear of the crossing back and forth that is our biggest issue.