My teeth are in good health and I take good care of them, yet I always get this plaque buildup no matter what I try.
I've tried different brushes, toothpastes, and flossing methods to no avail. Mouthwash is too harsh on my mouth and peels my skin off so I avoid that.
I haven't tried waterpicks or electric brushes yet. Did you? Did they work for you? Have you succeeded in preventing plaque and if so, how???
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.