Betta Fish: Betta fin nipping?

I’ve had my betta Lotus for about five months now and I’m concerned that he’s fin nipping or has fin rot. I’ve tested his water parameters and they appear to be stable , he has a sponge filter with low flow, a heater, live plants and driftwood along with dragon stone, a betta log & coconut hide. I made sure the dragon stone wasn’t sharp, and I did the same with the driftwood, I even filed down all the sharp edges. His tank is 9.5 gallons and was established months before I got him, and he is the only fish in his tank. I do a 25 % water change once every week and a half or so, sometimes 2 weeks, and I make sure to add water conditioner in the new water before I add it to the tank. I’ve given him a couple salt baths with aquarium salt, but that seems to really stress him out. I’ve done two feedings of frozen food mixed with Kanaplex, and have added tannin powder to his tank. I have Methylene Blue that I can also use, but he gets extremely stressed outside of his tank. He seems to swim around just fine and he gets really active when I come near his tank, and he has been eating well. He is on a rotation of ultra fresh betta pro shrimp patties, freeze dried mysis shrimp, frozen brine shrimp, and frozen bloodworms. I also fast him one a week, considering he eats the copepods and limpets in his tank, and I don’t want him to bloat. I’ve never seen him nip at his fins, but I’m not sure what else could be causing this. I don’t know if it could be his reflection that’s stressing him out, or the light, but I don’t keep the light on very long and sometimes leave it off all day. I will definitely be getting more live plants that he can rest on & Im contemplating removing all of the driftwood, rocks, and his betta log, just to see if that would help, but im not sure. I am really worried about him and want to know if there’s anything else I should do to help him. I know that long finned bettas are poorly bred and struggle with their fins a lot, and I will not be getting any more:( Will adding more live plants help, or am i going to need to move him to a smaller tank? I’m racking my brain about how to fix this, and I’m sure I left something out, so feel free to ask! I’m open to anything 🥲