How do I answer my questions in depth while not rambling on?

Perhaps it would be good to create a checklist of things to write in your essay, similar to the PEEL format for GCSE students or something slightly more complex for older students. It is important to memorise important pieces of information that you can use in essays in order to avoid rambling that you might do in order to cover the fact that you don't feel confident writing about the topic at hand. For practice, it might be useful to look at an essay you have previously written and highlight which bits of the answer are useful and answer the question and then rewrite your answer without the unnecessary parts so that you become more familiar with writing a concise yet in depth paragraph.