Feeling overwhelmed w/ loose threads and juggling plots - anyone else? Feedback appreciated!

If Ty, Joseph, Jacqueline, and/or Aegon stumble across this post, begone!

Hey folks. My party is currently in Vallaki, post-feast, and a lot has happened already. The module has been challenging for me so far as I find there is so much to keep track of on top of player-centric subplots.

I'd super appreciate any ideas for any of the following topics, or even sharing your own experience if perfectionism/imposter syndrome/burnout has effected you during your time DMing CoS. I feel pretty overwhelmed and would appreciate a push in, well, any direction, otherwise I'm worried I may have to throw in the towel as a DM. I do plan on expressing how I'm feeling to my players first, but my hopes are pretty low at the moment.

Anyway, on with the unresolved plots!

Milivoj and the Locket

I ran Mandy's orphanage encounter and fumbled it, hard. To make a long story short, the party "defeated" the demon and took the locket with them. That night, while they were asleep, the locket went missing (the demon possessed a random NPC in the communal sleeping area and skipped town). Now, the party is determined to find the locket again because they believe its the key to curing Milivoj, who is now comatose. I made a bunch of terrible decisions out of panic that I regret, but now I don't know how to resolve this plot point in a logical, satisfying conclusion for my players.

A Deal with the Devil

This was huge and I'm still reeling from the possibilities. After the party failed to reconsecrate St Andral's church and the Feast unfolded, one PC offered herself up to Strahd in exchange for calling off his vampire spawn and leaving Vallaki in peace. Obviously, Strahd agreed, so long as she would take a drink of his blood, and him of hers. Now that he has possession of some of her blood he gets a mega boost to scrying on the party hereon out, but I feel this could lead to something incredibly impactful down the line. I would love some ideas in how to execute this.

PC's Lost Mentor

This is a player-centric subplot, but any input is appreciated. The party's paladin(2/sorcerer 3) is trying to hunt down his mentor, who went missing a year or two prior on some mysterious quest to Barovia. I had planned that the mentor came to Barovia in attempt to uncover the history of their order (which had originally branched off from the order of knights in Argynvostholt) but met her doom, her soul becoming trapped in the mist and consumed by a Dark Power, which will eventually attempt to lead the PC paladin astray in the guise of the mentor. How she died, what sort of secrets she may or may not have uncovered about their order or Argynvost, etc. is unresolved.

Wolfshead Whistle

(This feels like a silly thing to be worried about but I really try to roll with what my players want to pursue rather than shutting them down.)

Rolled on a random encounter table during travel time. It landed on a wolf's head shaped whistle on the side of the road. PCs check it for magic, which it isn't. Barbarian still thinks its special somehow. Do I just tell him "no, seriously, it's just a whistle" or do I play into my player's suspicion and make it special despite what I've already told them?

Please be kind with any comments or feedback. Thanks!