Can you just be underweight without having an ED?

I've pondered this for awhile now because, well, I guess I *am* underweight... but I dont think I've got an ED. I've taken the quiz on PC multiple times and it says basically it's possible, but I don't know..

I don't *think* I have one; I mean, I've had many symptoms of some, but I have no problem with myself. I guess I am so-so on myself, too thin here, too fat there.. but I don't see an ED present, though a lot of my friends and family sometimes question me and my eating habits..

Ergh, I'm so confused and unsure >_<