Betta Fish: Does my boy have fin rot?

Hello, this is my boy Nemo. I got him out of horrible conditions (last photo), he was basically kept in a small bag the whole time he was at the shops. I’ve had him for about 2 months now.

My tank is a 8.5 gallons, has some drift wood, rocks and is densely filled with plants (rooted, on drift wood, floating). He lives with a school of rasboras that does not bother him.
The water is tested weekly and has zero ammonia, nitrite and nitrates along with 20% water change. He is fed Hikari Vibra Bites, Yee spirulina feed, frozen baby brine shrimps, the occasional bloodworm and live daphnia. He is eating very well (an absolute glutton).

Recently I realized he has some uneven edges on his anal fin. It hasn’t really progressed much since I noticed (from what I can see) and I cannot really tell if this is a really slow progressing fin rot or just mechanical damage from the wood/plants as he likes to squeeze in between them.
To me they don’t look like typical fin rot (fin not melting, shrinking, tearing further or look like it’s getting “eaten away”).
His ventral fins has always been this way (asymmetrical) and hasn’t changed.

Photos taken 6th Nov > last Friday > today (3rd and 4th photo).

Would be great if any experienced betta keepers can give their opinions! TIA 😊