Hi Lin, these may come handy: I’m preoccupied. Imagine someone knocking on your office door while you’re having a meeting. I’m tied up. I have a lot on my plate. I’m juggling a lot right now. I don’t have the bandwidth. I’m spread pretty thin. I’m swamped. I’m buried in work. I hope it helps :)

Marisol touched on some good ones. "I'm swamped with work" is another expression.

When you feel stuck at work you're saying that you feel paralyzed and you don't know how to change your job. You'd better say "I'm up to my neck in work" "I'm snowed under with work" Ï'm busy as a bee"