How to talk about problems openly with my boyfriend?

I've been with my boyfriend for a year and a half, but I feel like I still reserve some of my feelings around him because my nature happens to be extremely non-confrontational. I arranged to talk tonight about some fairly minor issues with our relationship, but whenever we do this I more often than not end up not saying what I need to say in fear of seeming too needy/demanding/annoying/over emotional. Either that, or I'll say what I wanted to and instantly regret it and try to backtrack what I said. Any tips? :(