My first question would be have you ever repotted it? That pot looks far too small for that tree (and what's the white thing?). And what's the black thing on top in the pic? And have you left the fake(?) moss on the soil from when you got it 7 yrs ago? You have allowed branches to grow quite long, but not (early on) pruned branches traditionally, but left e.g. ones growing dead opposite each other halfway up (can't see others well to comment) which ISN"T a crime if you prefer the look, but may have thickened the trunk there as much or more than at the bottom. But the small pot .... have you done any rootwork?