AITAH for going on my approved vacation even though my manager scheduled me anyway?

I (19M) work part time at Meijer. Back in early June, I requested 5 days off for a vacation before the request deadline. My manager approved every day on June 17, so I booked everything and made plans. I'll be out of state during those dates.

When the work schedule came out, I noticed I was scheduled on one of my approved vacation days. I left my manager a note letting him know because I assumed it was a mistake. Instead of fixing it, the schedule was updated again and I got scheduled on two more of my approved vacation days.

Ever since one of my coworkers got fired, we've been working 6-day weeks and covering what feels like two people's jobs, even though I'm part time. I've already worked 6 days straight.

I'm planning on talking to my manager in person, but if the schedule isn't fixed, I'm still going on my vacation because I requested the time off on time, it was approved weeks in advance, and I made nonrefundable plans based on that approval.

AITA if I don't show up for those shifts if they never correct the schedule?