Have you tried Stim-U-Dents? Dental plaque is a biofilm containing waste products (toxins) from oral bacteria, and is thought to cause gingivitis. It needs to be removed daily.
I use Stim-U-Dents, in conjunction with toothpaste and/or baking soda, to remove plaque from between teeth. Dental floss can also be used. If you haven’t tried them, consider getting some and trying them. In my experience, it takes about 2-4 weeks to clear up gingivitis.
I struggled with gingivitis/bleeding gums off and on for probably decades, until I learned how to remove plaque from my teeth. No more bleeding gums. A dentist taught me about this. It needs to be done at least daily. “It’s a process, not an event.”
If you have success with Stim-U-Dents, ask your dentist to order a case for you from a dental supply company. They’re much cheaper that way.