I imagine you've read the mantra here, "get a fitting from the bike store". If the LBS does this properly, you should be checked for proper seat height. They measure the bend in the leg when the pedal is at its lowest point, also there's a measurement based on the leg fully extended... I know because I had mine re-checked the other day.

But: I'm not sure if they pay attention to your hips rocking back and forth when pedaling. I would ask someone to check you on this. I don't think it's good for your back if pedaling causes this.

That's my 2 cents for the moment, I'm sure others will add more. I paid a lot of attention to the concept of being bent over on a road bike because I've had lower back pain for a while. In my case, riding hasn't aggravated my condition, but that's just me.