Since I've been sanitizing my brush head in hydrogen peroxide after each use to avoid re-introducing bacteria into my mouth it's made a significant difference in the quality of my brushing and minimizing plaque formation. Also, the main area to aim for specifically for plaque is where the gum meets the tooth rather than just all over the tooth hitting the gum incidentally.

For me I use Phillips soniccare tooth brush which is infinitely better than a manual one. Have you tried your luck with iodine mouthwash? It's more expensive and tastes gross but it's really good for gingivitis and doesn't burn. Also if you aren't already, flossing everyday and maybe after each meal if needed is important. Floss has to be reaching below the gums to pull out the trapped food and not just in between the teeth.

While I think brushing, flossing, mouthwash all play an important role. Nobody is teaching you how to breakdown the actual problem. Besides genetics if your hygiene is sufficient. The food and drinks you consume are to blame. Bacteria are influenced from your diet. Change what you consume and your bodily systems will adjust accordingly, that being said cause and effect should be noted. Changing one system will modify others good or bad. Tailor your intakes based on the symptoms your trying to mitigate by learning how those systems work individually and then cohesively together. The fastest way albeit quite inconvenient is to log every food, drink, and consumable item that goes into your mouth each day for X number of days and find trigger foods which cause your symptoms. Analyze and extrapolate the data. Refine through trial and error. Tailor your diet to suit.

You seem to be doing quite some things well. Maybe pay attention to your brushing? My dentist once had me brush my teeth in front of her and identified why in some teeth I'd consistently be clean and in others I'd consistently build plaque.

Her recommendations: brush from the gum to the tip of the tooth. Try to aim at the holes between teeth. Pay close attention to the part in front of your tongue, in your lower front teeth; that part can easily build plaque if you don't use the tip of your brush well to get in the holes between your teeth.

I use an electric toothbrush (Oral-B is very good), floss, a CBC mouthwash, and a tongue scraper. Sometimes I'll floss after meals as well. I've read that brushing immediately after a meal is not good.

Arm and hammer toothpaste with baking soda is great. Clinical studies have proven a statistically greater reduction in plaque than toothpaste that does not contain baking soda.

My trusty 16 year old sonicare toothbrush, a tongue scraper, and a water pik make it so I barely get fuzzy teeth unless I eat a bunch of sweets or crackers. I also swish with OralB gum detoxify mouthwash every once in a while, but I didn't have much plaque even without using it.

The other oralb washes aren't as great imo, but the gum detoxify has zinc and cetylpyridinium chloride in it which both inhibit bacteria. No alcohol in it either which is what causes most mouthwashes to burn. It does cause you to spit out a white film immediately after which I assume is dead bacteria. Never had any irritation with it and a doctor actually recommended it to me when I had strep throat which it helped.

Also Walmart carries a sonicare 1100 that is only around $20. I use that when I travel instead, and it's just as good as my older more expensive electric toothbrush.

I spent several years intermittent fasting, only eating between 6pm and 10pm. I didn't do it for my teeth but it did help keep them much cleaner, probably obvious in retrospect. It's not a healthy diet in a lot of other ways though.