You need to get your watering intervals under control. I'm nearly certain your issue is over-watering. Try using a wooden 'tell' stuck deep into the soil, all the way to the pot bottom, to read moisture levels deep in the pot where it actually matters. More on that below.

I'm assuming your pot has a drain hole. Yes? After you water thoroughly, so the entire soil column is fully wetted and at least 20% of the water applied exits the pot, tip your pot at a 45* angle to force more water from the soil. Compare B to A below to see what difference it makes.

What do you do insofar as fertilizing?

Using a 'tell'

Over-watering saps vitality and is one of the most common plant assassins, so learning to avoid it is worth the small effort. Plants make and store their own energy source – photosynthate - (sugar/glucose). Functioning roots need energy to drive their metabolic processes, and in order to get it, they use oxygen to burn (oxidize) their food. From this, we can see that terrestrial plants need plenty of air (oxygen) in the soil to drive root function. Many off-the-shelf soils hold too much water and not enough air to support the kind of root health most growers would like to see; and, a healthy root system is a prerequisite to a healthy plant.

Watering in small sips in order to avoid over-watering leads to a residual build-up of dissolved solids (salts) in the soil from tapwater and fertilizer solutions - which limits a plant's ability to absorb water – so watering in sips simply moves us to the other horn of a dilemma and creates another problem that requires resolution. Better, would be to simply adopt a soil that drains well enough to allow watering to beyond the saturation point, so we're flushing the soil of accumulating dissolved solids whenever we water; this, w/o the plant being forced to pay a tax in the form of reduced vitality, due to prolong periods of soil saturation. Sometimes, though, that's not a course we can immediately steer, which makes controlling how often we water a very important factor.

In many cases, we can judge whether or not a planting needs watering by hefting the pot. This is especially true if the pot is made from light material, like plastic, but doesn't work (as) well when the pot is made from heavier material, like clay, or when the size/weight of the pot precludes grabbing it with one hand to judge its weight and gauge the need for water.

Fingers stuck an inch or two into the soil work ok for shallow pots, but not for deep pots. Deep pots might have 3 or more inches of soil that feels totally dry, while the lower several inches of the soil is 100% saturated. Obviously, the lack of oxygen in the root zone situation can wreak havoc with root health and cause the loss of a very notable measure of your plant's potential. Inexpensive watering meters don't even measure moisture levels, they measure electrical conductivity. Clean the tip and insert it into a cup of distilled water and witness the fact it reads 'DRY'.

One of the most reliable methods of checking a planting's need for water is using a 'tell'. You can use a bamboo skewer in a pinch, but a wooden dowel rod of about 5/16” (75-85mm) would work better. They usually come 48” (120cm) long and can usually be cut in half and serve as a pair. Sharpen all 4 ends in a pencil sharpener and slightly blunt the tip so it's about the diameter of the head on a straight pin. Push the wooden tell deep into the soil. Don't worry, it won't harm the root system. If the plant is quite root-bound, you might need to try several places until you find one where you can push it all the way to the pot's bottom. Leave it a few seconds, then withdraw it and inspect the tip for moisture. For most plantings, withhold water until the tell comes out dry or nearly so. If you see signs of wilting, adjust the interval between waterings so drought stress isn't a recurring issue.

Al

trees are not easy houseplants...

lets see the pot.. when is the last time you repotted..does it go outside for summer ...

what supplemental light do you use..

what is the heating system. and does hot furnace air blow on it... that could affect watering ...

and reread everything Al said.. multiple times ...

ken

Thanks for responding. It’s in a 10” pot, when I changed out the soil I put it back in the same pot. That was a few months ago. There’s a layer of small rocks to help with the drainage. I haven’t put it out for the summertime. I use a 150W LED light. The only heat I’m using is a seedling heat mat under the pot (I read that warmer soil will help with new leaf growth). It’s not in any direct line of a heater. I definitey see that overwatering could be a problem. I thought I was under-watering it, and so was trying to give it a little more water. I do have a water meter that I usually use, so I’ll definitely try the tell method! I use a water soluble fertilizer every couple weeks in the warmer months.

You don’t need the heat mat. That will make the soil too warm and encourage etiolation and fungi. The normal indoor temperature of a heated home is fine for an avocado. Moisture meters are notoriously inaccurate and rocks don’t help drainage. If you can get the watering under control things should improve. Despite being trees avocados actually make quite good houseplants, though I would recommend summering outdoors.