OK so time for an update, I removed more of the branches and have taken a new approach so my last virt is now scrapped

here is a photo after the chopping, that was about three weeks ago.
Since then I have repotted and built another little grow/display box for it and some other experiments and it has started to back bud all over. I really like the shape this is taking and am glad I kept my options open before removing too many branches. Here is a photo of it as of today, the red line is where I am thinking about cutting to balance the tree out.
Here is a pic of my little grow/display box that I made using an old wine box, I am using two CFL bulbs which seem to be doing the trick. If you look closely you can see I have edited the pic to show what the little guy would look like after the proposed trunk chop.
So far I am really happy with the progress and general direction the tree is going. I think for now I am going to let this guy grow to regain its strength then when the time is right do some pruning to encourage backbudding and ramification. I do have a question about something that has been bothering me for a while now...
This is my largest and first plant, a while ago I did a fair bit of pinching around the apex to ramify and slow the top growth, this has worked and the leaves have also reduced nicely but they are a yellowy green colour in comparison to the older leaves. Also the lower larger leaves are wrinkled slightly as if the tree needs watering, however when obviously watered well they still stay wrinkly. I am curious if a co2 deficiency could be the cause of the wrinkling? I have been closing the grow box to keep it warm but poor air circulation has resulted. As for the yellow leaves maybe a Nitrogen deficiency? I am still trying to work out a good feeding plan, it seems to be growing quite slowly at the moment.
Any help and advice will be appreciated!!!
P.S sorry again if the pics are quite large