Prepare for a long journey my fellow barista’s and SSV

Hey all, I’ve currently been a barista for just over 6 months now and I’m transferring (told current manager it’s because of transportation but it’s because I work with LITERAL crack heads), when I went to see my new manager she asked if I had any upcoming days off. Just some important info here, I’m a chronically ill, disabled, teen (minor), and I’m transferring to a very small store (literally JUST got their nitro) with 4 other competing cafe’s on the same block. Anyhoo, I told her that I needed Nov 16th off when she asked and she happily wrote it down (this was well over the 2 weeks before the schedule was made). A week later, I opened teamwork’s and what do you know? I was scheduled on the 16th. And of course THEN I was told I also needed the 17th off. Well sh**. So I text my manager, telling her I’ll find coverage and if I can’t, I’ll just have to miss the event and go next year (it’s only annual). She texts back just: “I think we could make it work”. No punctuation, no thoughtful response (per usual), etc. Let me note, this would be my FIRST (and second) shift at this new store. No WAY am I going to make that impression. Text her back saying I would never call off w/o coverage and she texts back “Thank you for being that way (heart emoji) I will try to find somebody if you can’t!” Knowing my coworkers, she will not.

What the HECK do I do?? I’ve been looking forward to this event for the past two months and I know they would be fine with out me, to be honest, but I can’t make such a terrible first impression, yell at my coworkers some more? I literally cover for them all the time, I offered to trade shifts, and my tip money. Pretty pissed tbh