Rachelle-
I have the same problem as you, although we only have 7 kids. My youngest boy is 7 so I have stopped saving his clothes. If we did have another boy, the clothes would have been stored so long they probably would not be in very good condition.
With my girls 5, 3, and 4 months, I have saved everything (in good condition). But as Cora is growing out of things I am only saving the really great stuff and they rest I give away.
I was actually thinking about getting rid of my maternity clothes too. I have had them for a while and to be honest I am getting tired of them! I know if I needed maternity clothes again I could get decent stuff at the thrift store or on eBay.
As for the kids clothes, with yard sales, thrift stores and hand me downs from other families I am starting to only save stuff that is really special.
I still have about 15 totes, but that includes winter coats and boots... so it doesn't seem too bad, especially since now I have a basement to store it in!
Toni