It's never too late to start taking care of your teeth properly and that's what  seems to be asking about. Certainly, you cannot 'reverse' total decay but you can certainly halt progress, which is just as important when it comes to the rest of the teeth that aren't affected by decay at this point.

And more than that, gum care is just as important as the care of the teeth if not more important. Studies have shown that gum health also affects the health of your body overall.

So it's important  to understand that mouth care involves more than just brushing teeth with sonic devices and using some mouthwash.

Floss twice per day. Use stimulators to help stimulate blood flow to the gums and to toughen them up some over time. The healthier your gums are, the healthier your teeth will be despite your sugar consumption. Keep the gums healthy and your body will be more healthy for it. 

WHAT TO DO ?

  • Find a good dentist.
  • Be prepared that you will have to alter your life a little, both in terms of oral care and diet (which you've done), to see the rewards.

Keep brushing, that's great, but yes, you have to clean up your diet if you want to stop having decay. 

It can be done, but it does seem to be difficult for many people. 

We all have a bunch of bacteria in our mouths, our noses, our guts and on our skin. Most of the bacteria are beneficial and actually help suppress the bad bacteria. 

If you have gum disease or a lot of decay, somehow the balance has been tipped in favor of the bad bacteria.Bad bacteria also like sugar.

If you clean your mouth well, you eliminate more of the bad bacteria and tip the balance back so that more of the good guys are around.

Once you get the decay under control, have your teeth checked for gum disease and then make sure you have a thorough cleaning. 

As others have noted here, have them show you how to floss and then make this a habit. It takes less than a minute to floss and then several minutes to brush. I know you've got three or four minutes to spare for your teeth.

So it is not too late for you, but you do have to make some changes.