artificial vertebrae-insertion surgery??
 

I have such a short torso, to the point that it actually hinders my movement. I basically have no waist - the bottom of my ribcage nearly touches the top of my pelvis. It's like if I try to bend down and touch my toes, I can't even get halfway there - not because I'm not flexible, but because my bone structure gets in the way. Is there a surgery out there that inserts artifical lumbar vertebrae so that I can lengthen my torso and increase the distance between my ribcage and my pelvis? Someone suggested rib-removal, but this won't make my torso longer too.

Yes! this surgery exists, I'm not sure but I think it's not FDA approuved yet. It takes a lot of time for surgeries to be approved.
This doesn't mean it is not safe, it's a very safe surgery performed only in Germany, Dubai and Barcelona.
You'll have to search the internet but I even think that in Dubai it's performed by a US surgeon (not sure about that)
But just Google "artificial disc replacement" and you should get some information.

Let me know if you need some help...