rear brakes rotational noise/sound

my friend and I just installed new rotors and pads on the rear. Had a really hard time getting the right rear side rotor on and off, but had no issue with the left side. Now there is a squeaking rotational noise coming from what I think is the right rear side. I can only hear it when going slow (under 60km/h) and when the car isn't completely warmed up. It's there whether im off the brake, on the gas, or on the brakes. I'm thinking it might be the e-brake shoe rubbing against the rotor. Anyone have this happen to them or know what's going on? The sound is driving me nuts.

You could have got something between the pad and the rotor causing noise. Rigoursly spray some brake clean in there and see if it goes away. Do it to both sides, sometimes wheel well noises come from the opposite side of the cause.

we also may have bent the back plate when trying to pry the rotor loose

Which is why you don't pry rotors. You whack them on the face to dislodge them.

Since you have a gut feeling about the ebrake, go check it. Usually after you work on something, your gut is right about what the noise could be.