Thank you

Hello! I am very new at this and I am not even sure I am posting in the right forum. I have been having problems with my bonzai and I am desperate. It's a ligustrum tree (according to the label it came with) and it's been losing its leaves. I repotted it about a month ago and everything was going alright. However, during the past week it's started to lose its leaves. It looks alright and all, I mean the leaves aren't yellowish or anything and they look absolutely healthy despite the fact that they have fallen off.
Do you have any idea why this is happening?
I have been watering it regularly, spraying its leaves, using the right fertilizer (rich in iron etc) but there seems to be no improvement.

Could you please help me?

Thank you very much!

Aleka