The viral load with omicron is lower and not showing up on tests as readily. A positive test means you definitely have it. A negative test does not mean you definitely don't.

However, if you are testing negative you have a lower viral load and are thus less contagious.

That said, we all need to work on (self included) staying home when symptomatically sick anyway. (I find it particularly hard because I pride myself on doing what I said I was going to do, which now means I am terrified to commit to anything. Sigh).