Possible to add length to a tulle skirt?

I saw my dress on someone with a petticoat and loved the way it looked with the added fullness. I want to get one but am worried that it will make my dress, which is already borderline too short, even shorter.

Does anyone with a tulle ball gown have before and after photos of with and without a petticoat so I can see what it did to the length?

Or, is there any way to add extra length? The outer layer of tulle seems slightly longer than the inner satin.

Thanks in advance!