Betta Fish: Is this fin rot or am I just paranoid? 😭

Hello! The beautiful boy you see above is Lace <3

I bought him from PetSmart a little under two months ago. He was nearly solid white with flat fins when I first got him. I know bettas can change colors and whatnot when they get in a better environment but his fins are concerning me. They weren't curled up at the ends when I first got him, there's black spots in the middle of his dorsal and anal tail, and one of his ventral fins is super curled and dark while the other is a lighter color and longer.

I don't know if these are just normal things or what, but if yall could give me your advice I'd appreciate it ;;//

Tank size: 15gal

Heater and filter: Yes

Tank temperature: 78F

Ammonia, nitrites, nitrates, PH: All 0, PH is 6.8

Any tankmates: 7 tetras and 7 shrimp

What do you feed and how much: Twice a day– mix of bloodworms, shrimp, and daphnia

Decorations and plants in the tank: Live plants and aquarium safe rocks and wood