I'm glad your sister responded that way, that must really help.
On the dating issue - you made me smile.
I just ended a relationship with a guy who wanted to prove to me the seizures were in my head by switching my meds to sugar pills (like I wouldn't notice that the medication I've been taking for two years just happened to look a little different). Breaking up was devastating at first, as it always is, but earlier this week I found a button with a saying on it that fit perfectly. "It is better to have loved and lost than to be with a psycho forever".
I hang out with friends when I can, and have had the same response as you; most just want to be friends, and some just plain run for the hills. Mandi's right on the ball, as always you don't need to be with a girl who doesn't accept all of you. Right now I'm back to dating again, and at the end of our first date, I started getting the shakes. Josh asked what was wrong and I told him. His first response was asking what he could do to help, and even though it was mortifying, he stayed there with me, and kept talking to me afterwards, as if nothing were out of the ordinary. Amazingly enough, he even called the next day, and we've been hanging out with friends and going on dates for the past three weeks.
Don't give up, okay? My brother was single for almost three years, waiting for the right girl. Now's he's dating this incredible woman, and I love seeing them both happy. There's someone out there. Just be comfortable with yourself, be who you are, and when you're no longer searching for love, it'll be there waiting.