Please help, i really need advice about this girl i really like!?

[Ninja]

Okay so i really like this girl and i have done for years, she's my sister's friends and our families are really close but i've never really spoken to her, she's very quiet and shy around me. I think she is absolutely gorgeous and i want more than anything for us to get to know each other better and see where things go from there. I don't know why but she hates herself, she thinks she's ugly, stupid and worthless, she has no self esteem whatsoever. We follow each other on twitter and she always tweets about how no guys are ever going to be interested in her, no guys text her and how she thinks she just isn't good enough. Her bio on twitter used to say "dm me? ", so i thought i'd dm her so we we can get talking more (i don't have her mobile number yet) but here's what happened: One day i just said "Hey x" and she never replied, i thought i should really have made more of an effort so maybe it was my fault, anyway a few days later she came over and let us borrow a tv series on dvd, I thought i'd use this as a conversation starter and that evening i direct messaged her saying thanks again for the dvd's and i think they're really good, amazingly she replied and we got talking about this series for about an hour or so, she was really friendly and i think she did want to talk to me because she teased me about the fact i stayed up too late to watch these dvd's. As i started the conversation i wanted to make sure i ended it so i said i had to go and that i'd chat to her again sometime...bet she didn't reply to this! I left it a few days again, then i messaged her saying hey and asking how she is...no reply. I don't understand it, she always complains about not having a guy in her life, yet i'm here making an effort to get to know her better and she doesn't seem to want anything to do with me, she might not like me, but how can she not like me if she doesn't even know me!? I really don't want to sound cocky but I don't think i'm ugly, i've been told i'm a nice looking guy and I'm getting quite lean and muscly because i surf and go to the gym all the time so i don't think that's it. There's lots of eye contact between us when i see her, and we always wave goodbye when she has to leave our house even though we haven't really spoken. She tweeted saying for once she wants to fall for a nice guy...i'm a nice guy, i'd treat her like the angel that she is but she won't let me show that, it's so frustrating because it's only a matter of time before she finds someone else. I've asked her friends and they say she isn't seeing anyone at the moment so now is my chance, I don't want to send another message because I'll seem needy and will scare her off for sure, I can't deal with waiting around for her any longer though i feel like I need to do something! Does anyone have any idea what's going on in her head? My guess is she doesn't want to get too close to me because it might ruin her friendship with my sister, this is what i'm scared of because if she thinks like that it's out of my control. Please I really need some advice on what to do, I think the world of her, I want to make her the center of my universe and give her the love she so badly wants from a guy, maybe she doesn't like me but she doesn't know me well at all, i'm sure she would if she knew me better. Please anyone tell me what you would to in my situation, it's driving me insane! Sorry about the long post, it's just that this is really important to me.

[Hanna]

well i think you already know the answer
shes your sister's friend.
she probably only thinks of you as her sisters brother
&some girls, let me rephrase this, most girls are insecure of themselves so maybe that could be why? just compliment her, be nice and friendly
but i'd say move on? or you can ask your sister to help you out

[Skylar]

I think I read about ten sentences before I realised you had a WHOLE STORY! So I just skipped to the end.

I think she might like you but like you said, has never had a boyfriend before do she doesn't know how to talk to a guy that well. Keep on starting conversations with her, even if she doesn't talk back that much and she'll feel like someone wants her (if your sister can talk to her, I'm sure you can do twice as well).

From what you described she sounds like me and I like a guy that tried for me, even of I do nothing back, it makes me feel special!