Why can't I restore from iTunes backup?

[beerye333]

Ever since I upgraded my iPhone 6 and iPad air 2 to iOS8.2, they both run like garbage. Super slow responsiveness, blank screens when loading apps. Apps crashing etc. I followed the instructions to downgrade back to 8.1 by backing up my iPhone to my computer through iTunes, and then downloading the IPSW file etc. The problem occurred when I tried to restore the phone from my backup on the computer. Even though it clearly said "last backup performed 3/14/15 at 7:45pm", when I clicked the "restore from backup" button in iTunes, it only gave me the option of choosing a backup from September when I bought the phone, so I basically had to set my phone up from the beginning again. Was I doing something wrong, or was that my only way to go back to 8.1 because I hadn't backed up my phone since then? I want to downgrade my iPad too but I'm afraid I'll have to revert back to the way my ipad was when I first bought it. I guess the meat and potatoes of my rambling question is: is there any way to backup all of the current settings and apps, etc. that I have on my iPad running 8.2 so that when I downgrade to 8.1 I'll still have my phone set up exactly the same? Thanks for any help!

 

[beerye333]

That should ask if I could have my iPad set up exactly the same at the end. Not iphone. Sorry.