I don't understand why you can't just get layers put in; surely then the different lengths of hair wouldn't make any difference? If you want to disguise it better, try having your hair curly; the texture should cover up what you're worried about. I bet no-one except a hairdresser would notice it anyway. Maybe she was just after the 'kick' that hairdressers get after cutting long hair...
I do think that straightening is in general a terrible thing to do to your hair, though I acknowledge its addictiveness. What would be best would be if you could phase out the straightening and try something a bit more natural; just see what your hair looks like left to dry on its own and take it from there. Ideally, you should get a cut that involves mininum styling & damage and works more with the natural shape of your hair...if you insist on straigtening your hair, invest in some good heat protection products and use them every time without fail.
I'd think it'll grow out eventually, though the 2 inches off might be a nice change...it might be nice to have a fresh cut and a fresh start with it.