Turns out I missed the one right at the start. Sorry bout all this. So yeah I've got everything except the secret costume which I dunno where that is.
No problem at all. I actually don't know if anyone has found the secret costume yet. It's not necessary to get the best ending for the game, so I hope you don't mind if I leave it a secret for now. 🌟
That's fine, I'll simply live with the knowledge that I will never see it.