She's been watered 3/4 gallon of r.o water @ 6.4 pH with 13 ml's of cal-mag . Why are the leaves droopy if she's not over watered ?

Sorry, but I don’t see the problem you’re describing. Your leaves don’t appear to be drooping to me at all. They look fine. The leaves do look a little large, and their weight alone may be giving them that appearance to you. I would suggest some defoliation if some of the larger leaves that are drooping as you say, to see if it doesn’t provide more light to lower branches and improve the overall quality your plant. Honestly, I think your plant looks great. Just try to defoliate the larger leaves. But be careful when you do it! If you’ve never done it before, be sure to hold the stem at the base of the leaf and then lightly pull down to separate it from the tree. If you’re not secure in your grip you could end up breaking stems and branches off very easily. I think your plant is doing just fine the way it is right now. That would be my only recommendation for now. Good luck!