@Andy428
I think it's a good idea to go with the private room, shared home listings as @Ryan455 suggests.
https://www.airbnb.com/help/article/1864/how-do-i-link-airbnb-calendars-for-multiple-listings
But personally, instead of 3 separate private room listings I think 2 listings will work better since you only have 1 bathroom. The 2 private room, shared home listings can be Listing A - up to 2 guests and Listing B - up to 4 guests (and if only 2 book, you can state on your listing description that one room will be locked so the guests have the choice of a queen bed or 2 singles.)
For this to work, the guests will need to be able to lock their bedroom doors and you (or your co-host or cleaner) will have to drop by more regularly to check shared spaces and the bathroom.
If you don't want to bother with multiple guest groups.....then all you need to do is make sure your listing description and house rules explain very clearly that depending on no. of guests access to certain rooms will be limited. Good luck~!