NO plant likes root congestion. There are times when root congestion might serve the grower because it has an effect on the plant the grower likes, but that isn't a clear indicator the plant will like it. Tight roots cause stress and all sorts of physiological problems for all plants. It reduces growth, branch extension, and leaf size. It limits vitality and caused the shedding of older leaves proximal (closer to the trunk) to growing branch tips (apices). If anyone tells you that a particular plant prefers to be root bound w/o explaining what they really mean is some growers like to maintain a particular plant in root bound conditions, they're wrong. If "some plants" really did prefer root bound conditions, Mother Nature would surely have arranged the plant's genetics so it grew tight little masses of roots right under the stem ..... but we know there are no plants that naturally occur that way. That said, your plant probably isn't in any immediate danger that pertains to root congestion. You're better to suffer the limitations the plant is now growing under for a while in exchange for a more opportune time to repot, which for you would be next June. Plants have natural rhythms, during which their energy levels wax and wane. For major work, like repotting (which includes root pruning), it's best to ask the plant to endure the added stress of repotting or rejuvenation pruning when its energy levels are at peak - not now when they are at or approaching their lowest levels of the entire growth cycle. If you haven't read it, the link below should be very helpful. If you are wondering about repotting and how to maintain trees in containers for the long haul, this link offers lots of guidance. Al Here is a link that might be useful: Lots more info

It's not losing leaves due to pot size. It's light related or other cultural factors. Ficus trees do not go dormant in the winter. They grow all year, but usually slow down a bit during the winter. Yes it does look like it needs to be repotted, but you can wait until June without issue. id get it closer to the window. As in right up in front of it.

I forgot to mention, I just read in an old post that pale yellow growth could be caused by growing in cold weather, maybe this is the same thing and I shouldn't worry until summer?

Plants that are struggling seldom give you cuttings that will root, so it's a good bet that any attempt at starting cuttings would be an exercise in futility. New leaves on ficus are typically a lighter shade of green than more mature leaves, and it's not unusual for anthocyanin to express itself (the purple pigment dots) in new leaves. It will fade as the leaves mature. If the image represents the roots current condition, I don't see why your tree shouldn't recover quickly, though you might have slowed recovery down if you didn't keep roots dripping wet throughout the procedure. It only takes a minute or two for fine roots to dry out and die. Closing your tree up with only a low light source might well have caused a corky layer to form where the leaf attaches to the stem. This is called an abscission layer because it's the point at which the leaf abscises (separates from the plant). Once this layer starts to form, it's not reversible, so some of the lower leaves might still be shed. You have a LOT of leaves on the plant for the root system to keep hydrated, so you might also see additional shedding as a drought response due to a compromised root system. This would be do to the repot, but the roots drying out during the repot would add to your shedding woes. You could remove some lower leaves or just let the plant decide what it needs to do to balance the top to what the roots can keep supplied with moisture. As long as you don't over-water (moist or damp as a wrung out sponge is what you should aim for) your plant should do the rest. When you're sure it's pushing new growth, you should start fertilizing. HOW you fertilize, solution strength and frequency, depends on your soil and how you water. Key, is your choice of soil and making sure your watering habits are appropriate. If you're able to water to beyond the saturation point, so you're flushing the soil when you water. without the plant having to suffer because the soil remains soggy for extended periods, you already have half of the battle won. Al