Maybe repot it and see how the roots look. If your have rotten roots that would let you know your overwatering. It sounds like it could use some more light. Maybe look into a grow light to supplement your new apartments lack of natural light. Moving stress could be a part of your problem too. It might just be acclimating to is new home.

Yeah, your little monster is still a juvenile plant. I would move it over to a sunny window where it can receive more indirect sunlight. They don't grow well in lower light conditions, despite the fact that they grow in indirect sunlight. That's why it's shedding older leaves, because it's not receiving enough sunlight to support having and maintaining that many leaves. With that being said, these plants shed older leaves quite regularly as they continue to grow longer vines. Other than that, your plant looks very healthy.

For one thing, the fertilizer you've chosen depends entirely on soil biota populations to cleave the hydrocarbon chains in which nutrients are locked. That generally doesn't work well for container culture, reason being soil life populations normally cycle between boom and bust, with greater emphasis on the 'bust' part. Whenever mobile nutrients like N, P, K, and Mg are deficient in the plant, plant central recognizes the deficiency and starts to harvest nutrients from older growth to serve as the building blocks for what we view as new growth. If the deficiency continues to the degree the level of these nutrients is too low to allow the plant to 'pay back' what it has borrowed, the foliage is eventually shed. Since growth is measured by the amount of dry mass accumulated, even though the plant is extending, it might not be growing. In fact, the opposite can occur when plants are shedding more mass than can be replaced by new growth.

I'm not seeing enough young foliage to make me think the older foliage is being shaded to the degree it's being shed as a result of shade-induced hormonal changes that cause shedding. Usually it's a significant diminishment of light levels that reduces the flow of auxin across the leaf's abscission zone that causes an abscission layer to form, which essentially isolates the leaf from the rest of the organism, and I just don't see that happening unless you recently resited the plant to a location with considerably less light.

Circling back to nutrition, plants use about 6X as much N as P. 1:1:1 ratio fertilizers like 5-5-5 supply about 2.5X as much P as the plant wants/needs as a function of N. Excess P in the soil acts to limit uptake of at least 5 nutrients I can think of, just off the top. There's more, but my suggestion would be to switch to a soluble synthetic fertilizer with a more favorable nutrient ratio (more N in relation to the other nutrients), and use it regularly. I use Dyna-Gro's Foliage-Pro 9-3-6 for all my trees, other woody plants, houseplants, and succulents. Upping the volume of fertilizer you're using now doesn't ensure it will be delivered, and would compound the skewed ratio - especially over time, and especially if you're not flushing regularly as a way of hitting the 'reset ratio' button.

Your thoughts?

Al