The measure of growth is the increase/decrease in the plant's dry mass. Plants grow whenever they are capturing more than enough of the sun's energy (and turning it into food/carbohydrates/sugar) than it needs to keep it's systems orderly. The food is used to create new cells that are laid down in files that cause lengthening and thickening of stems and branches. Your tree is unable to or just barely able to keep up with this minimal demand. The most likely reason, based on visual evidence, is over-watering. When you over-water roots die, and the most important ones that do the lion's share of the heavy lifting (water and nutrient absorption) are first to succumb. This sends a chemical message to plant central that says 'stop growing until we have enough healthy root tissue to provide water and nutrients to support any new growth'.

So, you over-water, roots die, and the tree stops growing until the root damage is repaired. About the time plant central should be getting the message it can start putting on top growth again, you decide it's time to water, initiating another cycle of root death and regeneration that results in stalled growth.

There are many ways to break that cycle, but the best way is to repot into a soil you don't have to fight for control of your plants' vitality. If you can't water to beyond the point of saturation, that is to say so you're providing at least 15-20% more water than needed to completely saturate the entire soil mass, w/o having to worry that you're being set up by soggy soil for another cycle of root death and impaired function, you are leaving a very large measure of your plants' potential lying on the table.

There are a number of easy tricks you can use to eliminate all or very nearly all of the excess water held in excessively water-retentive soils (ask if you have interest), but removing excess water doesn't necessarily elevate the amount of air in the soil to levels that make the plant willing to show its appreciation.

Al