How do you all keep track of Infiniti maintenance without forgetting stuff?

Honestly my problem is not a broken car, it is my bad memory. I have a 2015 Q50 and it runs fine, but I realized last weekend that I have no idea when I did what. I think the oil was changed around summer, or maybe before that. The brake fluid, the coolant, the air filter, the gearbox oil, I cannot say for sure about any of them. I used to keep a small notebook in the glove box, but it got lost when I cleaned the car before Eid. Now I feel like I am driving blind. My wife laughed and said the car will tell me when it needs something, but I do not believe that. A warning light usually comes when the problem has already started. I found the paper manual in a drawer, and it has a long table with kilometers and months, and honestly it looks like homework. Some items say every 10,000, some say 20,000, some say 40,000, and then there are notes about hard conditions that I think apply to us because of the heat and dust. Then I read a page from a workshop in Mussafah about regular maintenance for Infiniti, and it explained in plain words why small checks keep big bills away, like looking at belts, fluids, tires and the battery before they cause trouble. It did not feel like a sales talk, more like a checklist, which I liked. Still, I want to hear from real owners, because I have been searching for Reliable Infiniti maintenance service in MBZ CityReliable Infiniti maintenance service in MBZ City and every place says the same nice words, so it is hard to know who actually does what they promise. Do you stick to one workshop so they know your car history, or do you move around to find better prices? Is it smart to ask for a printed report after each visit, or is that too much? Also, how do you remember the next service date, do you use a phone reminder, a sticker on the window, or an app? The car has about 101,000 kilometers now, so I am scared I missed some big item. Is there a way to find out what was done before I bought it? My brother says the dealer can pull the history from their system, but I am not sure if that works for a car that was sold privately. And one more question, if you follow the book strictly in this weather, does it cost much more every year, or is it fair? I would like a simple routine that I can keep for the next five years without stress. Thanks everyone, any small habit that worked for you will help me.