The problem is with the phrase "official LDS doctrine". It could mean any number of things: (1) what most Mormons believe, or believe should be authoritative, (2) what most Church leaders believe, (3) what Church leaders believe is authoritive, (4) the doctrines with which if you publicly disagree you could be excommunicated, (5) what Church authorities teach regularly, (6) what Church leaders have taught at least once, (7) the core doctrines as presented in Church materials, ( 8 ) any doctrines currently taught in Church produced materials, (9) only those teachings found clearly in the standard works, (10) ditto 9 but with first presidency messages that are also signed by the 12 apostles, (11) ditto 10 but also including official proclamations just from the First Presidency, (12) ditto 11 but also including any talk given by the President of the Church in his capacity as President, etc..., etc..., etc...
Furthermore, there are levels of authoritativeness, interpretation, meaning, and understanding -- even on the questions of what we should take as authoritative, how we should interpret scripture, what certain sermons mean, and what we should understand the gospel to be about.
Let me give you a few examples from my own life to demonstrate how this all interplays.
Example 1: As a missionary I knocked on the door of a retired Baptist preacher. This was about the time when the Baptists were coming to Utah, and so they had been taught what the Mormons (supposedly) believe. As we talked he asked me "Are you saved by grace alone." Well, I felt that was a tricky question because of the word alone, so I answered "That is a good question" at which point he interrupted me and asked again: "Yes, that is the question. Are you saved by grace?" Well, that question was easier to answer. "Yes," I said, "I believe I am saved by the grace of Jesus Christ." To which he answered, in utter disbelief, "You don't believe that!"
Clearly this man was wrong. I did, and do, believe that. However, implicitly he was making the claim that that is not the "official" doctrine of our church. In this case, almost all of the different possibilities for "official" I listed above would agree that in fact this is the official position we take. I imagine that there are the occassional talks from church authorities which may lead some to question this view (especially our view of how works tie into exaltation), but nonetheless this is one of those clear doctrines.
Example 2: Reading blogs about Mormons, I often come across comments like "Mormons believe that God lives on a planet named Kolob." Well, Kolob appears in our scriptures right? This should be an open and shut case of official doctrine right?
And yet, I cannot recall the last time (if ever) I heard in General Conference anything about Kolob. It just isn't a central part of our teachings. Further, the scripture itself is not entirely clear. But even above that, in another place the word "Kokob" is used, which is clearly the transliteration of the Hebrew word for star. It isn't meant as a name for a certain star, or anything special. So that makes one wonder if Kolob does not similarly represent the transliteration of a Hebrew word with origins like "Kokob". Mormons are not punished for offering differing opinions on this subject.
So is "Kolob is God's planet, or God's star, or nearest to His residence" an official doctrine? In some senses, and not in others. It certainly is not central, and as stated is highly misleading.
Example 3: Reading the Journal of Discourse, Brigham taught all sorts of neat things. Some of them God has told me are true. I believe them. Are they official doctrines? Again, it depends on what one means by the term.
Example 4: A nonmember sincerely wants to know what Mormons believe about a subject they hear about, like the priesthood ban. Perhaps they want to be able to even teach others what we believe. What is our official doctrine on that topic? It is my belief that one cannot even begin to try to express what Mormons "officially" believe about the ban without first explaining what one might mean by "official", what the history is, what the current theories are, etc...
So to sum up: I just don't see a simple answer to your question. Each of the simple answers already given are just specific interpretations of what "official" might mean, and there are multiple meanings available. Mormons (in my experience) are only interested in what is "official" in the sense that it helps them classify what is standard, and what is authoritative, in an effort to uncover what is true. Truth is what really matters to us.
Thanks, Zeta.. I am beginning to see that it is, indeed, very complicated!