Hamelia patens var. Glabra: Questions

Hi All,
My questions are about any advice you may have - please! - on helping my tree grow healthily and develop a thick trunk. Both short term and long term advice appreciated. Here are the details!
I've had a Hamelia patens var. Glabra for about six months now. It was bought as is in the photo. The trunk is about 38 cms tall. At base, trunk diameter is under 5 cms. There are many branches pushing upwards and outwards from the main trunk. Those branches in turn have some more branches.
I fertilise using homemade fertiliser (rotting plants+some sugar+human urine) every two weeks.  The pot is 40 cms (about 20 inches) across and shallow. I have added some perlite and cocopeat. Maybe 10% of the soil is perlite/cocopeat and it is mostly at the bottom of the pot. I give it about half a litre of water everyday. Apart from this, all I can say is that it is kept outdoors all the time. The temperature varies from 45 degrees centigrade for around six to eight months per year, to 10 degrees centigrade for about three to four months (110 to 50 Fahrenheit). Most of the time the 'Firebush' is in the shade in my balcony.

Any help much appreciated,
Thanks
Dattaray