It is August/2019 and is next to impossible to find a Dublin area B&B for 5/2020. Do I really want a Holiday Inn Express Room or the like ?
Maybe it is too early to book?? Sometimes I think they don't open bookings until six months out.
As Gail suggests, it is too early to book most small family-accommodations for next May. Try in November or December.
If you can narrow down your preference list, maybe just email them and ask whether too early or really fully booked.
My experience booking for June '20 was that a lot of (good) places seemed to be filled and the one I settled on was not taking bookings until December of this year. Nervous about not getting a place we liked, I booked a nice room over a pub a block north of the river across Liam Mellow's bridge. McGettigans Townhouse. Pub serves brekkie in the morning too.
I see that Premier Inns (UK brand) have opened up in Ireland. Not sure it is much better than Holiday Inn Express, but I found them adequate....though breakfasts are hit and miss and expensive added cost.
Note: almost everything else we booked in Ireland(Northern, Killarney, Valentia Island, Cashel, Portmarnock) took our booking 6 months ago. That's why we were a little concerned about getting the 3rd choices...
Did you try The Albany House? I just finished booking all the hotels for our May 2020 trip. I feel your pain! www.booking.com helped out a lot.