So I just came out to my mom (yay!) But after an initial, weird reaction she had ("uhh... why would you tell me that?"), she proceeded to tell me that I shouldn't "tie myself down with labels" because I'm only 13. After that, she said that I shouldn't tell my friends. Not only that, but after the fact, I feel worse than before... I don't know what that means.
Give her some time to digest what you have told her...it's not an easy thing to get your head around. And maybe direct her to some information, explain the process you went through? And I kind of agree about your friends... For now...while you've obviously put a lot of thought into this, are they likely to understand? Hell, I've only recently learnt what asexual is, other 13yo's are generally not going to have a clue.
She probably just thinks that you should give it some more thought. She doesn't want you to tell your friends in case you change your mind. I don't think she is trying to mean or unsupportive by reacting that way. Being 13 years old it might be hard to tell exactly how your sexuality will be in a bunch of years, after all.
Not talking to your friends doesn't seem like all the best idea to me. The best way to feel comfortable with them is when you tell the truth. I do really believe your mom is right about the fact that you shouldn't tie yourself to a label just yet. Give it some thought, but tell your friends about how you feel, it usually is easier when you explain them what you feel, rather than burying them under a lot of terms. I do want to congratulate you on coming out! You shouldn't feel bad afterwards, what you did was not an easy thing to do, yet you did it, and your mom probably needs some time to figure it all out. Best of luck in your future!
I don't think there's anything wrong with sharing what you're thinking and feeling with your friends - that's what friends are supposed to be for! In terms of labels, I think your mom just doesn't want you to feel like you've boxed yourself into a certain identity. If you attach to a label, you may feel obligated to do or say certain things just for the sake of being consistent with the label. At this point, rather than worry about a label, why not just spend some time exploring?