How to get an accurate prescription?

I have two different pairs of glasses at home, and I can never get a straight answer about my vision.
Basically, my prescription is different for each eye, and the last doctor I saw actually suggested I shouldn't even bother with glasses because the correction is too minor...

I’m looking for some advice—where can I go for a thorough, high-quality eye exam?
Has anyone here had experience with the General Electric clinic?
I'd like to schedule a full checkup.

Thanks