My sister has been ignoring me lately?

My sister is 16 and I am almost 14. She has been my best friend for as long as I can remember, but for the past couple of months she's been really distant and ignoring me. I think part of it is because even though I am at a healthy weight, I am always worried about my weight and she doesn't want to get involved in that. I was anorexic last year, and I almost relapsed recently, but I remained a healthy weight. One big reason she is ignoring me is because there is this girl in her grade who is her new best friend. She is always on the phone with her, laughing and chatting, and doesn't respond to me at all. Yesterday, she was on the phone with her, and I said, "Hey, Leah (let's pretend her name is Leah), where did you put my boots?" and she'd not even look at me but would continue her conversation. And then when she's not talking to her new best friend, she's really distant. Like today, when she woke up this morning, I gave her a huge hug and she shrugged me off. Then I said "I love you," and when she didn't reply, I said "Leah, I said 'I love you'," and then she blew up at me saying "GOSH, why don't you just chill out!? You're so annoying." I don't know what to do anymore. She is my only close friend. I have many friends at school, but they all get on my nerves and so I rely on her to sustain my social life.