Brake Job, Stuck.

If you are sure that you have pressed the piston all the way back in, you get to do two things:
1.) Pull the rotor off and have the thickness miked. Make sure it meets the maximum thickness spec for new rotors.
2.) Pull the pads off and mike the pads, inner and outer. Use a new set of pads by some other manufacturer and compare the thickness.

You get to replace whatever doesn't meet spec.

Put those pads on a belt sander to get them down a few until they fit. Not the best option, but its free. 1/16th off each pad you wont miss it. Or turn the rotor down like was mentioned above.

--Chuck

Personally, I don't recommend sanding the new pads. Breathing that dust isnt great for any one (I used to sand pads back in the day - I had a situation kinda like 5L5 noted. It was a rare car and I had no options). You can end up with some waves or even crumbling chamfered edges if not careful.

Jrichker's advice is right-on. You can wing the measurements with a Vernier caliper if you have to. Your repair manual should note max rotor thickness and perhaps max pad thickness in the specifications section. If not, just as JR said, compare your pads to a set from the parts store. You cant necessarily do the same test with rotors because some parts store rotors are near min spec out of the box. They're not meant to be turned.

Good luck.