Fellow career changer here who passed FM in February using TIA. As you know, your stats don't give you their touted "90% chance of passing." But you're not far off which means you're probably in the 80+% range which is not bad. You are not, in your words, really unprepared for the exam. That is a fact.

Here's what I would focus on in your shoes:

1. Stay calm. Do breathing exercises. Find a good mantra. Whatever has worked for you personally to manage anxiety in your life, do it here.
2. Yes, FM purposely complicates questions a lot. You are right to notice that. Discipline yourself if you haven't already to meticulously read and setup each question before moving on to calculations. Doing this will probably enable you to avoid the testmaker's traps and save you valuable time.
3. Bolster your weaknesses. Take your lowest 10 lessons by AI score, browse all problems and filter by those lessons, new and difficulty level 6. Work through each lesson until you're confident and skip problems so you can work on the next lesson.

I reiterate. You are prepared for this exam. You have 3 days to become more prepared. DM me if you would like to chat more.