What is wrong with my jade plant?

Hello!
My jade plant used to be strong and have firm, bright green leaves. It looked healthy! Now it's leaves are dull and droopy. Even the stem feels fragile. It has a south facing window with a lot of direct sunlight during the day. I've had it for about a year now. Is it possible it is acting like this because it needs to be repotted? I have maybe been watering a little too much recently... Once, sometimes twice a week although never a lot. How often should it be watered in the winter? It is on the window sill above a radiator but there is a bowl of water on top of the radiator so the air is a little humid.
Also, what is the white fuzz on the plant?
Any help would be greatly appreciated! Thank you,
Sian

White fuzz might be mealy bugs - try Qtip dipped in alcohol.

It's not getting enough light.

The soil looks inappropriate (fine and water-retentive)

You're probably watering in small sips, which ensures salts from tapwater and fertilizer solutions are building up in the soil, skewing nutrient ratios and making it very difficult for the plant to absorb water and the nutrients dissolved in water.

Per what the above poster offered, it may have a mealybug problem.

I suggest you start by reading the sticky thread at the top of this forum. It has information that will help you avoid all the issues you're probably facing now.

Poor soils and poor light are deal breakers. You can't expect a healthy plant w/o appropriate light and a healthy root system.

Al

Hi Sian,
Your plant is extremely dehydrated, that's why the leaves are so dull, soft and droopy.
The position above the radiator, the clay pot and the incorrect watering all aggravate the situation. A good watering practice is to drench the pot heavily until the water comes out the drainage hole (which is essential to every pot!). Drain the saucer - never let a succulent stand in the water. Repeat after the soil has dried out, which might be once a week or more often, depending on the climate.
Crassula ovata does not need a winter rest period, as long as the temperatures and the light is sufficient for growth. But then water accordingly.
Do not change the position of your plant at this stage, it seems to get enough light.
It probably would benefit from a repotting, but do not do this now as the plant is too stressed. Let it recover first, you will soon see when it is happy again.

And for the white fuzz - yes, this is probably mealiebugs. If there are only a few you can easily squash and remove them with a toothpick or skewer stick. But do check any other nearby plants, they might be infested too. Spraying with methilated spirits does help, too, if you don't want to use insecticides.

Good luck and keep us posted on the recovery!

Regards, Maddy