I would say that most theists would say god IS a supernatural energy that governs our universe (among other non-sensical things). 

Yes. By the fact that you define it as 'supernatural' it is irrational. When you label something as supernatural you are removing it from being anything that can exist in any way in which we as humans can understand the term existence. You are effectively rendering it a non-concept. There is no rational reason to believe that anything has this property of being supernatural, or any way to even understand what this 'supernaturalism' entails. Name a 'supernatural' quality by which we would know something as 'supernatural'.

If you don't have a belief in a god you are by definiton atheistic, or without a god belief. Agnostic means without knowledge, so one can be an agnostic atheist, or one without knowledge of the existence of any god and therefor without a belief in any god. In the end, since the terms are merely labels applied to express something about ourselves to others, it is the label you feel comfortable with that you should apply. Just realize that if you apply the theist one, you are by definition, irrational.  

What is the difference? The difference is in the "human-like" qualities associated with typical theistic gods(you seem to be likening your skepticism towards pantheism). For example, the Christian god created man "in His image". "His" probably doesn't make much sense for something that doesn't reproduce anyway, but the quality is still applied. Theistic gods, like the Christian god or Thor, any of the Egyptian gods etc. all act, generally, like people. They do things because of some personal motivation, no matter how divine or correct it might be(according to the believers). More than that, in most cases Theistic gods concern themselves in the everyday workings of the universe, specifically in the lives of humans; intervening from time to time with miracles, punishing sins and answering prayers. The "god" you're proposing; "may be something like "chi" or something deeply spiritual within us or our surroundings, like some kind of energy or prescence." would not have these personal qualities, and would not have illogical human traits associated with it. That is, as I see it, the difference between the two beliefs; One believes in a personal god who has motivations and reasons, who listens to prayers and intervenes within the universe and cares about what happens there, the Other believes in a "presence" of some sort which is responsible for governing the laws which are at the heart of our universe, who does not engage in abstract thought processes which could allow for the caring of sins and lives of humans.

Is this presence irrational to believe in? That depends on the way in which you define this presence. As is Dawkins' position, mine is that you're using the wrong word to describe what you're talking about, though. To call energy "god" is somewhat nonsensical; god has come to mean, in the minds of almost everyone you meet, a supernatural intelligence. It is certainly more rational, but I wouldn't place it at the same level of rationality as, say, believing that you will one day die.