Hi my brother Yousef
I felt the same thing, too, and I think the reason for this is that you may had read so much and as a result you created good amount of vocabulary about things maybe you haven't read about in Arabic so consequently when you try to discuss the same subject in Arabic you feel uncomfortable and let me give you an example as a medical who has been studying in English I feel more comfortable when talking about medical stuff in English than Arabic so it seems that it's down to the terminology and which language you use most in different aspects of life.
