At least 18,000 SF
I have the same living situation and it’s hard Getting stuff put away but it works out okay
I would recommend 1800 sq. m.
For just two adults, why a second bedroom? At 750 SQ ft. You should be able to find a nicer one bedroom and avoid having an empty bedroom that you walk past all the time.
You definitely want two bedrooms. My husband and I lived in an 800 sqft house with 3 cats! It was a bit too tight with one bedroom. We redid the basement to get an additional bedroom, laundry room and tv room and it was so much better. The thing with having a small space and not enough rooms is there is nowhere to go to be alone. Thus, if you have a small place you need enough separate spaces for you both to be completely alone to do your own thing outside of the bedroom (as that is shared space and somehow different). A second bedroom/office gives you that. 😊 So, you can go that small if you have enough separate spaces but I found 1200 much more comfortable space wise (post remodel)
Min 2500
1000
My 1br is smaller and works out fine with the same cat:human ratio.