Archiving Photos

I don't know where else to go for this and I'm not sure this is even the right place but googling it got me the wrong answer.

I have a lot of professional photos from conventions. 46-48 that I need to protect while the others are in frames. They're 8" x 10" which is an awkward size.

I bought comic bags and pocket pages for 8.5" x 11" prints from Ultra Pro. To fit the comic bags inside the pockets, I have to fold the edge and I put all my photos in the 2" binder I got from them. They're the wrong size but they were the only ones big enough to fit my photos available.

I put all my photos in them and inside the binder but they bend which I don't want. So I bought some A4 greyboard as backing board. I got 2mm ones because I thought 2mm isn't that big but they were way too thick and would make it so my photos wouldn't fit inside the binder. I returned them.

I googled what size comic backing boards normally are and it said 24pt or 0.6mm so I bought some 0.5mm greyboards but I think they're too thin. They're really flexible and I don't think they'd stop my photos from bending. But I can't be 100% sure because to know I would have to cut the board and then I'd be unable to return them.

Does anyone know what size would be right for my situation? Should I get the 2mm again and put my photos in a box instead? Would 1mm thick ones fit with 46-48 photos and keep them from bending?