He does not look bad at all. I don't have experience with ammonia in the water. Usually i would recommend just more water changes with mild case of fin rot or tail biting.
I am wondering if you can lower the ammonia with ammo chips or Prime and do more water changes?
If your betta don't have any behavior changes and if his fins don't ger worse do not treat him with medications. Especially if you already treat him before. And i am not sure how old is he but if you manage to keep him like that i think he is fine. I am not sure how he was before though. Your fish looks pretty healthy. Those black ends are you sure it not his natural coloration?
If you don't get answer on cycling or if you still have problem with ammonia i advice you to pm Sakura8 or Oldfishlady to look at your post. I would think they might give you advice.
But i don't really see how it got so bad because his fins don't look bad at all unless you will really think it will get shorter and shorter , more ragged, more black at the ends.