i do not know whether I will be of much help, probably not, but for me it helps being estimulated by what I say. Additionally I tried to explain things as if the other person was a 5 year old, not assuming they know anything about it... with me it helped
I think your English is just fine, too. If you have to opportunity to spend some time with native English speakers, maybe that would improve your confidence a bit. As you see that they can understand you, it will encourage you, and the words will flow more easily.