Trouble With Eye Contact, Any Correlation to ADD or Other Conditions?

I work retail @ Walgreens and find it extremely difficult making direct eye to eye contact with customers, especially when put on register... hell I even have trouble looking at my parents in the eye, kinda sad. But however I have gone through periods of increased confidence where I was not afraid of this situation. I don't think I'm a bad looking guy, I've even been told this by different people, but however this seems sort of like some kind of mental block & something I would like to overcome, especially to help me meet someone. And by the way, I notice my pupils tend to be quite large the majority of the time, does this correlate to anything? btw, I added the suspicion of ADD to my question because I think I have read someone before that this may be a symptom. Plus I think that having a furrowed-brow makes me come off as some sort of jerk, when I'm really not! Oh and my speech tends to be a little slurred too, lol, ok I'm done!