I just want to say that although I realize the OP wouldn't have posted here if she didn't have a problem, I've really enjoyed reading all the insightful advice others have given her. I have also known people who've stayed with others for five years or more, only to be told at the end that no, we're never going to get married, which they had been hoping for.
OP, it sounds like you've already talked to your BF about a lot of things, which is good. The timeline discussion is also huge, though. I think you ended by saying you were going to give it a year and see if you two had progressed to specific goals, like saving up enough for a house together--right? That sounds like a good plan.
I'm torn on the "little comments about the future," though. From what I read, when you would say things like, "When we get married..." and he would get very uncomfortable, it did seem like you were assuming this would happen one day, and he was clearly not assuming the same thing. It might be a good idea if you stopped making the comments from a base of the assumption that they'll come true eventually; but I don't think you should have to stop making the comments altogether. Maybe try, "If we get married..." or, "Someday, at my wedding..." without necessarily drawing him into the scenario, and see how he responds. At this stage, I think he shouldn't cringe at those statements and deflect discussion--he should either embrace them as his own goals or discuss why he doesn't agree. I don't think such important, life-altering events such as marriage or having children should be "hot topics" that are best avoided with a partner you've been with for this long. But, perhaps you just need to reframe them to be more hypothetical, like, "How many children do you see yourself having?" as opposed to, "How many children should we have?"