I have read and looked at many pics re this plant. Mine is about 15 yrs old, if not more. I really want to make it more bushy and I feel the only way is to cut it down to nothing. From this pic you can see it has one trunk on the bottom and two branches, one with no foliage til the top and one with foliage half way up. I don't want to kill it what is the safest way? Also, it stays indoors, should I wait until Spring is officially here to do anything?