I think that living together first is a good idea. I have been married & divorced twice. The first time I cohabitated & felt pressure from everyone b/c of DS. If I had it to do over again I would have just lived with him & never gotten married. The second time I didn't cohabitate & we couldn't be happy living together. SO & I bought a house together 5 yrs ago when I was preggo with DD1 & we are still happy. We have still not gotten married but I finally would. It's not a big deal to me as I know we'll be together either way.
My issues in the past were that I looked at marriage as a way to be with someone forever. That level of commitment can't magically fix problems so I've found for me knowing that someone is always going to be there means more than the piece of paper!