You can say,

“If you’re busy, then I won’t bother you.” or “I’ll let you go.”

It is possible to take on more hours or other PT jobs. It’s all about how many hours you want. Normally, what would happen is that you would one job with a school consisting of how many hours, usually 25-30 hours teaching classes (Hess and other bigger chain schools do 40 hours right off the bat), and then if you would like more hours, you can ask the school for more private tutoring hours with kids who need help. Or you can always go out and find students who want private tutors. The possibilities are endless.

I’m real glad to stumble onto your website. I’m in the States now too and thinking of going to Taiwan to teach for a year or two. Do you have any ideas as to whether it is possible to take on more hours or other PT jobs? I think the normal FT job might not be enough for me to cover some expenses in the States and would need to make more on PT jobs. Any advice you have would be appreciated!