As if I am not short enough, one of my legs actually has the nerve to be shorter than the other.

It is causing me to have knee pain. My GP recommended orthopedics inserts and referred me to a local specialist.
While not covered by my insurance, they are affordable. But I always look before I leap (or commit to spending significant funds). I would appreciate personal experience in the efficacy of wearing orthotics. I also have questions about whether or not special or different shoes are required.
I have different shoes for different occasions including hiking. Are the devices portable from shoe to shoe? I also have a high instep which prevents me from putting pads under the entire length of my foot. There is not enough room in my shoes for my feet and padding that goes too far forward.
Thanks for any feedback.