@Rebecca1635 Your place is really attractive and nicely furnished.
I think you could list the den as a second bedroom.
But your guest count is too high. 6 is way too many in a 1 bedroom, 1 bath place. You do not have dining room space for 6 nor living room space for 6. Forget any mention of an air mattress. You have a nice apartment, not a camping listing.
Just because you can cram more people in doesn't mean it's a good idea. It's a bad idea- you don't want to give guests the idea that they can cram in more people than there is really space for- before you know it they'll be 8 in there.
It may also very well lead to critical reviews, guests saying the place was too small for 6.
I don't understand the little tables next to the beds that have a plant taking up the entire surface. Beside tables are where guests put their phones, their book, their eyeglasses, a glass of water, etc. They serve a purpose, they aren't just something meant to be decorative taking up space. They each need a reading lamp on them and nothing else. And the bedroom needs a bedside table and lamp on both sides of a bed for two people, not just one.