My umbrella tree is slowly losing leaves. They turn brown and fall off. I transplanted it about a month and 1/2 ago to a bigger pot (not too big). When I first brought it home, it was losing leaves like crazy. So I transplanted and it seems to have slowed down losing the leaves. I have it in an east window with all my other plants, and I water it when it is almost dry. The plant is about 12 inches tall. What am I doing wrong? I've been growing plants for about 30 years, so I am surprised with this one.
If it was losing leaves right away, it may have arrived suffering some stress.
Your watering sounds correct, but make sure the soil is not draining to quickly.
Look carefully for signs of bugs or insects.
Here is a link that may help your determine a cause.