Are you sure you formed all the necessary covenants? There are no other requirements as far as I know. You're probably missing someone. If I had to guess,
the Tweedle Twins are probably the easiest to miss on a blind run, or possibly Shisha from the forest maze? Or even Bill at the cathedral.
Filling the library is not a requirement for any of the endings (I'm almost sure?) but you do get some very nice options as rewards. Some of the fairytales you mentioned are, well,
gone if you don't have them already by this point, since they need to be summoned before boss fights.
I don't remember all of them, but more specifically:
Aw maaaaaaaaaaaaaaan, so I've definitely gotta do a New Game plus then. (Cuz yeah I did not get that fairy tale)
As for covenants yeah, I'm pretty sure I've got the most of em already done. Like 13 out of ?? are lv3.
But I'm going to go the next cycle regarless since I can no longer open the white door or give up on the quest.
Which kind of feels dumb, since why do I have to play the game 2 more times just to see what happens if I decide to die to the final boss or decide to give up on the quest beforehand? Eh, it can't be helped. So I'll just go do something simpler.
Go for the hidden route! By pure chance I managed to meet
on several places and even got
ring alongside 3 of the Memories. Now I have just to find the others. But I dunno where those are.
Either way I'll go look for those memories now and then at the next cycle, if there's even a next one. Go about my way to catch all em fairy tales. Maybe even make a seperate save before the part where you choose an ending too for once.
I'd love to fill the gallery on my own true, but eh. It was less time-consuming in BS1, which I can't say here.
That all said, I hope the hidden route will unlock that 'opens all of the gallery' that the true ending of BS1 did. That was pretty nifty if not rewarding. Still this game as a whole is real fun, and again, it's a real pleasure to be here.