In scleroderma, edema can occur from many different causes, as you've likely heard from your doctor by now.
When I've had it due to skin thickening, I've gained up to 30 pounds in a few weeks and I couldn't even wear most of my shoes. Water pills and anti-inflammatories helped a lot with that but sometimes it is also a matter of just waiting it out. That sort of thing is definitely something to see a scleroderma expert about.
I also get edema from just sitting around too much, or having my legs down too much. It helps for me to use an easy chair whenever I'm relaxing, as elevating the feet reduces the swelling and can even prevent it. Sometimes just too much salt in the diet (usually, hidden salt, like in any processed food) can make my hands or feet swell up like balloons.
Usually its all easily remedied, by putting my feet up, getting more activity, not sitting around so much, watching salt more carefully, and drinking the right amount of fluids. I say right amount, because dehydration can also cause fluid retention, which is a real catch-22. Its good to keep electrolytes, in general, in good balance.
Over time, you will gradually learn what's causing the issue for you, and how to avoid it. It's good your labs were normal, that is always a pleasant starting point. But after awhile, your primary care doctor will probably become immune to the situation, and poke at the spots and go, Huh, and move onto another subject -- once they are comfortable that the worst causes (organ failure, blood clots, etc.) are ruled out.
If you don't already have a recliner, I'd recommend getting one, because they are comfortable and because I find it more enjoyable to be in the recliner than to try to prop my legs up on always toppling pillows in bed. And, keep us posted, let us know how things are going for you, okay?