You're so young, just a tender thirteen and I don't want that to take away from anything because your feelings are just as real as anybody elses. It does sound like you have a lot going on.
1. Your weight - you have realized that you eat for comfort and that is a huge step. Maybe you could try a program like overeaters anonymous, it's a great twelve step program that is free and is a place you can be totally honest with other people. Or just see what you see and exercise and try to eat healthier, see if that works for you.

2.Your family - It sounds like you love your sister very much and you just want some of that love reciprocated. Your concerns for her are very real and honest. It's good that you can see your true feelings, that you're not hiding your feelings behind the food.

3.The anger - cutting is a coping mechanism, albeit not a very good one, but nevertheless a coping mechanism. The key is to find out what is making you so angry. If it's the need for more positive attention you may be able to say to your parents that you need more positive attention, especially from your dad if you have one. That may help. Also, learn whether you like a. seeing the blood or b. feeling the pain of cutting and then try to replace that with something that doesn't do so much harm, like a red marker or a rubberband. Sounds silly I know but it does eventually work.

4.Your Looks - right now you're at an age where looks seem to matter to everybody and it seems as though everybody is always analyzing you and everything you do. That will be the feeling for a while, at least until you get a few years older. Just try to hang on the knowledge that you are beautiful inside for just who you are. You don't have to be super skinny and unhealthy. Those women are happier than you necessarily, some of them are miserable and anorexic/bulimic just trying to keep the look. Very few people come by that look naturally. Just accept yourself the way you are and others will admire your self-esteem

5.The anger - again, try to acknowledge what is causing the anger, the root of the problem. Is it the lack of attention from boys? or from your dad? Give yourself a timeout when you feel the anger rising, just say mom I need a timeout right now. Then when you feel it leave go back to her and talk.

6. Love - comes when you don't look for it. As long as you are happy with yourself that confidence will shine through your personality and be a huge turn-on. Guys like women who are confident it's more sexy than being thin with low self-esteem. Know that whatever body type you have there is a man out there that will be attracted to you specifically. You just have to wait and know that the time will come. I promise.

You have a lot going for you. You have a family that loves you. A family that you love and that's important. Having that core connection will last a lifetime. Try to make a list of positive things in your life and think on the bright side. let yourself see what you have going good. and ask for what you need. Most of all love yourself so when others love you, you will be able to understand what that is.

All my love,
Tara