Having virtually no life, I have spent the last few years amassing many books about Coleridge and his poetry. I doubt there is another poem in the English language that has generated so much written response in the way of full length books, not to mention the nearly innumerable essays in an attempt to capture the meaning.
I can advise you that there is no general agreement regarding the poem. I have read erudite opinions ranging from the poem expressing Coleridge's feminist nature, the chasms and fountains have a deep sexual meaning, the poem was a deliberate part of a tryptech of Kubla Khan, The Ancient Mariner and Christabel and many many more.
As I believe I mentioned in the post Les referred you to, as Coleridge was under the influence of laudanum there seems to me to be no absolute reason why the poem should make sense. At the time Hazlitt described the poem as nonsense verse. He may well have been right in the sense of the poem not having any particula meaning or sense to it.
Remember also that Coleridge always described it as a fragment. Fragments in themselves do not have to make sense.
Essentially, you can start with a blank piece of paper confident that the great and mighty critics of the last two hundred years have been attempting, without much success, to find a meaning. No reason at all why your individual essay should not contain at least as many truths as theirs. Don't be overwhelmed, simply write as you understand it having read it several times.