One of my legs is a little longer than the other - maybe 1/4" - 1/2", I forget. In fact, 1/2" leg length difference, if I remember right, is pretty normal.
I've wondered if it was because I had a cast on one broken leg for 6 months - or if it was always there.
It is somewhat common in figure skating to compensate by adding extra layers to one of your insoles, not necessarily just in the heels. The thing is, that can perhaps compensate for total length differences, but you may also have different differences in the sections above and below the knee. Boot modification can only go so far.
Bear in mind you may have to re-assess how you balance on one leg, and you still need to try to avoid lateral knee bends. I think that when you stand on one foot, your knee should be horizontally centered on your foot. People worry a lot about lateral knee bends, especially on jump take-offs and landings, where you can easily do yourself damage.
One of the consequences of my leg length difference is that the bottoms of both my feet are laterally tilted - something easy to compensate for in insoles. Before I did that, I had to constantly use a lot of muscle to keep both sides of both feet in uniform contact with the bottoms of my boots, which created major muscle soreness. It also resulted in a poor custom boot fit, because the fitter had me stand with both feet at the same time on impressible foam. The fitter then tried to compensate (badly) by mounting my blades way off-center (he should have modified the insoles instead), which twisted the boots out of shape.
Unfortunately, you can't easily order and replace body parts.
Why can't we do that? I'd like to order a brain transplant into a new custom-built body that better meets my needs. While I'm at it, I'd like to order a little extra memory and processing power for the brain.
Until someone comes out with a purpose-built-body catalog, you may have to compensate by modifying insoles, or, equivalently, adding inserts. Play around, and you can make it work.
I wonder if there are serious gymnasts and such who've had surgery to make their bodies more symmetric...
Be glad you aren't a growing child. Growth spurts don't have to be symmetric, and the center of gravity changes too. If I understand correctly, kids often have to modify skating technique after a growth spurt. In addition, they often need new clothing, and, if the foot size changes, new skates, sometimes every few months! Must be expensive. I once bought a barely-used pair of skates that had been used by a growing child. (I'm relatively short.)