MagnoliaMS,
I feel for you! I have several things in common with you here. I also went from 5'5" to barely 5'4" - complete bummer. Especially since my weight hasn't gone in the same direction.
My hips also were pretty comparable in terms of both needing to be done yesterday. My surgeon told me "flip a coin"; I chose the one which looked a little more deteriorated on x-ray, thinking I didn't want any more deterioration to happen. This was actually the leg that was slightly less painful, because somehow the muscles were somehow fractionally less compromised. I didn't have any data on length discrepancy.
So I had the one done in November, and the second 15 weeks later (this Tuesday). In general, I'm told, any leg does become somewhat lengthened with the procedure. I did notice a slight difference with the operated leg feeling a bit longer - no concern because I knew the second surgery would shortly follow. The day after my surgery, my anesthesiologist told me there was a very significant discrepancy found and that the surgery time had doubled while my surgeon worked to match the legs up (I always seem to get the inside scoop from the anesthesiologist rather than the surgeon). When I asked my surgeon about it, he said that although he put the exact same hardware in each leg, that the anatomy was different in the second one, so he had to spend some time making adjustments to make the length match (and I'm not sure whether this one was longer or shorter). Totally downplayed there being any real issue and I knew better than to push for any more information. He said that on the x-ray it looks like my leg lengths match. Being only a few days after surgery it's too early for me to tell; my surgical leg is still very swollen and stiff and doesn't move normally anyway. I am trying not to worry about it.
Based on my experience, Magnolia, my only advice is to direct your very good question to your surgeon. Let him/her know about your concern with leg length, your history with it, and if that is more of a priority than taking care of the one that hurts most first, let them know that. It seems like they would just try to make them match as well as possible, but maybe they can intentionally stretch you out! Good luck and let us know how your appointment goes. Kim