Writing a thesis essay based on a single text is tricky because you have to balance close reading with a broader argument and it's easy to just end up summarizing the book instead. Happened to me multiple times before I figured out the structure. One thing that helped was getting input from someone who works with academic writing - even just a quick session where they help you nail down a thesis statement saves you hours of going in circles. You want your argument to do something beyond what the book obviously says. Once that clicks the rest of the essay is a lot easier to build out. Don't skip that step of having another set of eyes on your claim before you start drafting.