From my experience I can tell you that I don’t think stuttering itself blocks happiness. What seems to do that is the conclusion that life has to stay on hold until we speak perfectly. A lot of people achieve things and still feel stuck because their lives becomes all about the one thing they lack or not so perfect in. The painful part isn’t the stutter. It’s the years spent waiting to feel “fixed” before participating fully. Do not think in the way of having to be perfect to allow yourself to be happy.