You have an amazing ability. You will have no problem getting others to understand you when you give that lecture/speech/talk. (just razzin' ya)
Seriously, Grz/br, you have nothing to worry about. I think you would also be a great English teacher. They are in short supply. I hope this encourages you.
I don't believe it's so much an ability to write the English language that's important so much, as the ability to be understood succinctly with the spoken word. I fail miserably in that department, and it's why I love internet forums more than being in person with someone I am trying to communicate with...(although it certainly has its drawbacks, like NOT being in the other person's presence)...but I digress....
I would suspect you surpass at all levels of comprehension.
My hat's off to you...and...I might add...I feel like I will be missing out on an incredible experience by not being able to hear you speak.