Thanks for the additional details. Bearing in mind that I'm not a network professional (unlike some of the other folk here) ... the impression I have is that your floor plans look pretty sane in isolation, but you've done them as though there's no signal transfer across floors. For instance the ground floor kitchen AP is at serious risk of interference with the second floor master bedroom AP. You mentioned that you've tried to assign non-overlapping channels to avoid that, but there's so few non-overlapping channels available in the 2.4 and 5GHz bands that I doubt that that approach can avoid problems. It seems quite plausible to me that your best solution will involve fewer than six APs.
On the whole though I agree with the other respondents that your big problem is you've got more clients than ASUS gear is built to handle. You need to move into SMB-class gear that is built to deal with hundreds of clients. Omada and Ubiquiti and Aruba are decent names to look at, or you could consider Cisco if money is no object. Somebody here recently recommended
Evan McCann as a reliable reviewer of gear in this space, and that definitely looks like a site worth your reading time.