Hun, I dont know how much I always stress this, but do NOT take what other people think of you into consideration when you put your clothes on, when you do your makeup, when you eat your food, when you look in the mirror, anything! I HIGHLY doubt you are fat. You are a dancer, you have to be in pretty dang good shape to be one of those, I will tell you now, I am 21 and not in good shape (I am healthy, but not fit), but even dancing around with my son for a while to some of his songs I get a little out of breath, which goes to show, you have to be in dang good shape for the stuff your doing. Do not let anyone tell you that you are fat, overweight, getting a little chunk, etc. No one has any right to tell you what they think your body is starting to look like because for one, it isnt THEIR body, for two, there is nothing wrong with being skinny, average, chunky, or fat. As long as you are healthy, there is no problem. I am 228 pounds, married, with a child. And if I can go through life being a bigger person and still end up living happily ever after, then you (the dancer, the one who is in good shape) will have absolutely no problem at all as long as you make the right choices lol.
If you think you might be beginning to become anorexic, then that is your first sign that you need to stop worrying about your weight so much. If you even think there is a possibility of it, then you are watching your weight too much and probably not eating enough. You will be 14 this year according to your profile, so at this stage in your development, you will most likely put on a few pounds, but that is COMPLETELY normal. You are getting out of the kiddie growing cycle and entering the adult growing cycle (which is VERY different from the kiddie growth cycle, everything develops differently now), which means you will probably gain a few pounds, but then you will get a growth spurt and you will most likely look skinnier at the end of the growth spurt than you did before hand due to your body trying to even itself out for the final stages of development. As long as you are eating properly (3 meals a day, and having snacks throughout the day along with those meals are fine too), excercising like you should (being a dancer you probably get more excercise than ALOT of people), and just staying active, then you will be fine.
I am starting to repeat myself and blabber on, so all in all, I think you are probably fine hun. You sound like you are healthy, at a healthy weight, and since you are watching for warning signs of anorexia, I dont think you would actually go so far as to become anorexic because it sounds like its something you dont want (we dont want it either!). If you think you are having problems with handling weight and stuff, then talk to your mom, she will most likely understand what you are going through because she was once your age too and went through this same thing. If your mom isnt around, talk to a female adult that you are close to, seriously, because they dont mind helping, and weight issues are a MAJOR factor in social, emotional, and physical problems in teens nowadays and you dont want to be one of those teens.
If you need someone to talk to about this, my PM box is always waiting for mail, I am a "bigger" gal so trust me, I know what its like to deal with weight issues. I am always around.