There is several things you could be missing:
To avoid spoiling too much, all I can say is.
17 Badges isn't the max.
There is currently 4 Sidequests ( 4 NPC), and one of them has 2 stages of completion.
I have done everything apart from those two things, which is why I am bit confused, do you know why the cat has a star? or can you only fight him once? Since idk if you can get to lvl 15?
So far I have interacted with every NPC I believe? so unsure what to do, main quest section done, it just those two. I will delete this message after but I on side quest section, says Sis Dojo and battle at lvl15, cant get to lvl15 due to cap and I did the 3 challenges, I have spoken too every other NPC in town?