You can continue adding divisions into each cilinder by moving the symmetry "mirror" point...
However, at all I would say to not continue this way... it will look good but probably the topology where one bark splits into 2 will be a mess and willl be noticeable on the rendering even later smothing groups will be updated....
For me would be way better to.
A: create Cilinder... make sure at least have some subdivision on the top...
B: use extrude on half the top faces of that cilinder... llater, do the same to the other half...
C: use relax on the object...
😧 subdivide the later extrussions and repeat the process of extruding the top face...
I add one image of it so can be undertood easier... (its a lazy work so it looks worse it could be)
PS: Instead cilynders, would be better to do it alll based on a cube (square barks insteasd of cilyndrical) willl make way easy to keep the quads / loops better... then a soft turbosmooth or a combination of tesselate + relax, can "fill the gaps" and finish with a much more "organic" look and of course with rounded edges.