If I decide to go to the seminary am I committed for life?

In no way. In fact, most vocation directors agree that the only way to really know that you have a vocation to the priesthood is to go to the seminary and try. It will become more and more clear to you once you are in an environment where everyone is trying to discern that same question. Many men go to the seminary, stay a year or two, and then leave. They are much better Catholics afterwards for the experience.