Hi there!
When I sold my old car, it was at somewhere between 120-130k miles at 14 years old. (The dealer offered me £300 for it.)
When I was looking for a replacement car, I really struggled to want to spend several £1000s on a vehicle that had done anything over 60K miles.
And low mileage older cars caused similar cognitive dissonance: "Huh! I'm not paying £10k for a 6 year old car that's not that much different (in day to day function) than my old one, which is worth £300, so I'm told."
Eventually I bought a 12-month old low-mileage car, which was way above my original budget, but felt better value.
Despite doing my research and planning what I was looking for, a lot of that went out of the window when I came across the "right" car, and the buying decision was triggered by a price check to make sure the agreed price was okay.
I tell you this, as your perception of value is something unique to you, but actual market value can vary wildly from your perception.
So my advice is to buy something you feel is good value, but check the market value to ensure you're not paying more than you have to. Good luck!
Note: Salesmen were absolutely useless at offering buying advice, blooming hopeless!
Edit: Just re-read your post and seen your car is £10K for 6YO car at 90K miles. Personally, I wouldn't touch it with a barge-pole, especially as you do a lot of miles. But I'm a tight old git and to me, 10 grand on a car which will have over 100K miles by next year seems too expensive.
But then we're back to perception. If £10K for a 6YO 90k miles car seems okay to you, AND the market agrees, then who am I to argue? Follow your gut feeling on it, but check the market price too.
2nd edit: Something that helped me, was looking at the cost to change, which in my case was pretty much £10K, and asking the question "What am I getting for my £10K?". I played my own bank-manager / Devil's advocate. Having to justify spending £10K on a car when I already had a perfectly serviceable car stopped me pulling the trigger on a car for some time.
That said, it is perfectly okay, if you have the cash set aside, to fall for a car, and just want it, without any other justification than "Oh wow! I really want that car! " That's perfectly okay. I rationalise replacing my old Mondeo, saying I sensed big bills were gonna happen, and it was going rusty, older diesels are going to be priced out of low-emission zones, etc. but a big motivation in changing car was that after 10 years, I just fancied a new car. And as I'd saved up for it, that was all the reason I needed to buy one.