I think you should keep doing it, Daily, though I know that kids your age are less tolerant of other people's movements and way of expressing and interacting because kids begin to judge other kids based on their "maturity" and they define "maturity" as never showing excitement about anything and moving your body in the accepted "girl" way. They will grow out of that when they get into their 30s and 40s and the ones who don't, well, you, probably won't care about their opinions by then. That's a long and painful length of time for you to suppress yourself.
My daughter was upset the other day because the other kids have been telling her that she is "weird." I asked her what she is doing when they tell her this and she said it's because she is flapping her hands. I asked her why she was flapping her hands and she said it was because she likes the way it vibrates. I told her that if flapping her hands makes her happy then she should do it. I pointed out to her that she sees me do a lot of weird things and that it is okay. I was trying to "normalize" these behaviors. There is nothing wrong with the behaviors. Rather, there is something wrong with the way the behaviors are perceived by others. If you sense that it is seen negatively, by others, then there is nothing wrong with giving a short nonchalant explanation. Guys are really good at these things, I have seen. You could watch them for how they do this and slip into that copy mode you might have. Even if the other people are still unaccepting, don't care about it. This is about you and your physical and mental health, not their minor discomfort or embarrassment.
If you flatten your natural body movements and try to act too much like someone else, you will be holding in all kinds of emotions and sensory stress and you may not even know it. You could end up with more meltdowns, more shutdowns, more anxiety, and anger outbursts than ever before. You could try to adjust the stim to something else less noticeable if you makes you more comfortable or less conspicuous, but do not shut it off completely or try to stop it completely. If you want to silence the hissing sounds, analyze what you really like about the stem, what you are really getting out of it. Just because it's a noise doesn't mean you are doing it for the noise. For me, sound stems are not so much about the sound as they are about the way it feels in/on my tongue, mouth, throat, or chest. But when you are happy, it's very, very easy to make the hissing sound. Is it like a Ssss sound?
Another thing, I think you shouldn't suppress stims that result from emotions*, and actually most stims do occur with emotional provocation. As a person with ASD or ASD characteristics, your nervous system regulates your emotions with movements. *If you know that your stim will seriously offend or hurt someone else's feelings if it happens at the wrong time or the wrong circumstances such as at a funeral or during a wedding ceremony or some other solemn or quiet situation, then you should try to be mindful of it beforehand so you can be considerate of others' feelings.
I hope I haven't confused you. There really is no straightforward way for this situation. You have to weigh the consequences and the circumstances and experiment with things and analyze your own needs and desires to deduce what you really should do with this and come to a conclusion for yourself.
And don't forget no one can see you at home or when you are alone and they cannot intuit what you do "behind closed doors" so feel free to "stim up the walls.''
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RDOS Aspie Score: 145 or 144/200 Aspie, 68 or 57/200 NT
Defies categorization. A mixed bag.