I know EXACTLY what you mean... I used to feel that way. I was like that for a long time, and then for some reason I just stopped caring.
Why is that? Well, let's just say that basically all of the reasons that I stopped caring about that you said in your post. You said that you and this guy "really like each other, talk about the future and meeting someday". In fact, it was the situation itself that made me stop caring!
And I had thought the way you thought for a long time. What if she doesn't like the way I look? What if she thinks I'm ugly? etc. Then I found it really stupid.
Here's the way I think (back to you now; if you didn't know, I know how you feel because my situation is much the same). If he says that he wants to meet you, doesn't that mean something? He says he really likes you and all of that. Does that mean nothing? That means a lot more than what you look like. Also, he has already seen your picture... so he has an idea of what you look like (even if it is your best picture; does that matter? When you meet, you'll probably dress yourself up to look your best). The funny thing is that it doesn't even matter, because when he says he likes you, he says that because he likes you on the inside. The chance of it being lust is incredibly small. Why? There are a lot of attractive, hot girls just about everywhere. So if he wanted to get with a girl because of looks or for lust, why not get one who is there? There would be no reason to go for a girl who lives a ways away, because there isn't physical contact!
That's not to say that people aren't different in real life than they are online. They may or may not be... but you know, the longer you know somebody (talking on the phone helps, too), the chance of them being way different is, well, lessened until it nearly disappears.
I would not worry about your looks to this guy. What if your self-conscience prevents you from actually planning to meet him? Would you rather have that?
I really didn't think so. You're just fine. The last thing I will say is this: it doesn't matter (much) to him what you look like. He finds your soul, heart, and mind beautiful, which means SO much more than stupid looks. There's also this thing about when you start liking someone for the real them, they get so much more attractive in your eyes.
If a dream comes true... then is it still a dream?