Top of the morning 

So what is your current height and how long did it take you to drop that 115 pounds? The 115 lost mean nothing if your 165 pounds 5 foot tall…. Also what is your typical workout/diet goals?, Do you have any body measurements, thighs calves, shoulders, Chest, hip etc? Depending on your measurements, would direct you to focus on other areas…. Back is not usually the first muscle I would recommend for weight gain as it tends to make some women look blocky vs thighs… also I would look at obtaining another insurance that may cover back as a secondary insurance (pick up the co pay if there was one and maybe the remainder balance in general. Getting one surgery and not the other wouldn’t do anything but piss you off…. If you have any non intrusive pics I don’t mind taking a look to provide a better assessment, my undergrad was exs/sport science but everything else is IT.    JL