Welcome to the board. As someone with a number of handicaps myself, I can tell you that God can use anyone. The way I see it, we're not any less of more of something than the "normal" people, we are individually created in a unique way. In other words, God knew how to build us best for His glory.
Since I've come to see that my inability to read nonverbal language, etc. easily is likely not just my poor vision and/or hearing, but may be a very mild Asperger's (undiagnosed, right on the cusp) it's actually helped me to appreciate how God built me more and to see just how amazingly He can use anything in our lives. And, the fact that God doesn't need us to be the best missionary or preacher or anything - he loves us just the way we are.
The world just can't do that very easily; they always seem to want more, and often find it very hard to accept someone who can't meet their own expectations of things. But God doesn't look at thigns like that. God sees a wondrous creationa nd says, "You're fearfully and wonderfully made" no matter how different fromt he world we are.
John 3:16 (KJV) For God so loved the world, that He gave His only begotten Son, that whosoever believeth in Him shall not perish, but have everlasting life.