Forward: In the world of fish there are a lot of opinions so you will get various reads on the same thing. An adage is "The only thing concrete in aquatics is nothing is written in concrete."
Did the fin damage happen over time or rather suddenly? If it was the latter (even if it's become worse) it's doubtful he has fin rot. From the appearance, he has been fin biting and has damage, possibly, from decor. Fin rot is normally a slow-developing issue where the edges of the fins are not clean but, rather, look more like burnt pieces of paper.
In addition, your maintenance and the 0 ppm Ammonia also gives me serious doubt that this is fin rot. That is 99% caused by long-term filthy habitat which weaken fish immune systems and leave them open to infection. Finally, actual fin rot is extremely rare. In nearly eight years on this Forum, 90% of suspected of fin rot was fin biting.
Indian Almond Leaves and plain, decaffeinated Rooibos Tea have antifungal and antibacterial properties so as noted, they are good to keep in his tank. Those, along with weekly 25% water changes, help stave off fin rot.
What worries me more is his body shape. He looks awfully thin. Can you post a photo of him from above? While older Betta do tend to be thinner, I'd like to make sure. For comparison, his body should look like a bullet with no indentation behind his head and a straight spine:
View attachment 1025218
As Mbpoppy noted, there are many fine foods out there. Omega One is okay but there are others equally as good: Fluval Bug Bites (best for insectivores like Betta), New Life Spectrum, NorthFin Betta Bits, Aqueon Betta or Color formulas (not "Betta Pro"). Fluval Bug Bites come closest to providing an insectivore with what eats most: Insects. I can find nothing from Omega One that indicates any of its foods will help heal caudal fins so I have contacted them for comment.