@Bart248
This is your competition and it looks like there’s a lot of it:
http://www.booking.com/Share-VkGbuX
(Smartflats Premium)
Their price for a 2-BR is nearly $200 per night and your apartment with that wonderful balcony looks much nicer, so at less than $100 per night it’s a good bargain for guests.
If you initially asked half that I’m not surprised that you got quick bookings. There are always certain people looking for inexperienced hosts with low prices and they are often not very nice or appreciative.
Your cohost should be warned to be careful who she allows into your apartment.
As for possible improvements, I would suggest some homelike decorations on the walls. Look at the competition to see what they are doing.
I understand that you may prefer a stark, post-modern style and it’s your apartment so you have every right to keep it that way.
On the other hand, you might have a lot of fun hunting for quirky decorations at thrift stores and flea markets and you can always put them away when you get home if they annoy you.
Airbnb’s recommendations regarding prices, policies and discounts are not to be trusted.
Low prices and big discounts often attract the wrong sort of guests.
High prices do not seem to be a barrier to good guests.
Good luck to you, keep adjusting your listing, and I’m sure you will be successful.