First, your plant looks as if it's in a small black pot contained inside an outer pot. If that's the case, it needs a bigger pot, so repot into a larger container using new potting soil. Second, when you water, don't ever leave water sitting in any outer tray or pot, so make sure that is emptied 30 minutes after watering, once the plant has drained down properly.
It's likely your plant has been restricted by the size of pot, so has been unable to grow well because the root to soil ratio isn't right - its hard for a plant to take up sufficient water if the rootball is solid, and water is unable to be retained by the soil for long. Repotting it will likely solve the problem, but its clearly getting quite a bit of sun - those red edges only develop with exposure to strong sun, so I suggest you might like to move it somewhere it doesn't get quite so much sun, just from now till end of summer, then sit it back in that spot again, if there's room in a larger pot.
Watering should be done when the surface of the soil feels just about dry to the touch, but not so dry its shrunken from the sides of the pot. Water thoroughly, and let the excess water drain away from the bottom of the pot, and, as already said, don't leave it sitting in water in the outer pot. Reducing watering slightly in winter is a good idea, but the same rule applies - water when the surface feels just about dry.
Otherwise, more information here https://www.gardeningknowhow.com/houseplants/jade-plant/jade-plant-care.htm