Personal items sold at a loss

I sell personal items online, typically at a loss. This is a regular occurrence; I post and sell items nearly every week. Would this be considered a business or a hobby since the most profit I'll pull in a year is maybe $100 or less? I do set out to (hopefully) make a profit, but I'm also realistic and accept that I most likely won't.

Also, how do I show that I have losses on nearly every item I sell? I have receipts on nearly every item I've purchased, as they were purchased online and for my personal use.

I know there are different forms that need to be filed if something is considered a business or a hobby, so I want to make sure I'm doing things properly and (somewhat) know what I'm doing.

Thanks!