What type of climate are you in and do you use any sort of fertilizer? Does the caudex (trunk) feel firm or soft? Looks like it could use some more light, but I think you mentioned that already.

Second (third?) the light. Also, more water + fertilizer.

i brought mine indoors when I moved and put it into my "sunroom" (it's basically a bedroom with an incredibly bright skylight rendering it useless for sleeping) and then I forgot about it for about a month.

Same yellowing, crunchy leaves and eventual drop.

I took mine back outside and it's coming back nicely. But it doesn't sound like that's an option for you due to your balcony location. It also looks too big for a grow light, I presume...

When I lived in a condo a few years ago with a balcony, I bought these hanging thingies that take my pot (and the plants in them) to hang outside/off the balcony. That bought me about 1-2 hours additional light, which made all the difference. The overhang on that balcony was such an issue for me. Maybe you can find or build something similar?

Just a thought. :-)

If you want more compact growth, assuming you can find a good way to provide light, you can also prune it back. Depending on where you live you may want to wait until the start of spring to do this. be sure to leave 3-4 inches of each branch coming from the caudex so it can branch out.

Also if giving it more water (which you should) make sure the soil drains very quickly and you can use a smaller pot so that there is less soil to retain water. Gritty mix is also a good idea if you're afraid of over-watering and is a favorite on these forums. Roots can rot easily in any standing water or if the medium remains too damp, but it is supposed to be treated more as a tropical.

By the way there is a specific forum for these trees as they call them. GardenWeb Adenium Forums. They can probably help you out more than myself as I'm no expert... yet :)

The thing with the smart pots is that they drain out the sides and the root ball is easily left very dry after watering.

I would first use a little bit of perlite in with your mix just so it doesn't stay soggy. I had one of my alpes in something heavier than usual because of the smart pot aeration but I had to switch over to using dry bunny poo as an aerator for that plant. The plant loves it, I just can't tell my husband that the one plant he actually checks before he waters it....has rabbit poop in it.

With my smart pots, I try to immerse them in a bucket of fertilized water instead of watering from overhead.

If I were you, I'd trim back all that lanky growth. Here's what I did with mine. Before: July 21, 2015

Thank you, Husband for holding the pot while I take a picture.

Then: July 24, 2015

And now....I have to put on my hijab to get a picure, but it's coming! All those leaves dropped (oobviously from being outside in the heat and not used to it but it's growing like crazy now). I hope it's photo worthy by the time I get out there. My Husband says it looks good...but what does he know?