Adding a title

This guy and I have been seeing each other for almost 4 months. But we haven't made anything official yet.  I really like him and would want to move onto the next phase of our life together.  we don't see any other people anymore. But I don't want to be the pushy girl who mentions a relationship first and force him into something .  How do I know when he wants to start making the move and talk about our relationship. Should I wait for him or should I say something. I know it's just a title like boyfriend and girlfriend but it would mean something to know that we are in a official relationship. Help!