Anyone trying to make out that what you do in your room isn't completely normal is lying or deluded.
So what if there have only been a couple of billion people doing the exact same thing since you last did it? Like I said, completely normal.
But it is private, so yeah, keep it to yourself, don't be noisy, don't leave evidence around and don't boast about your great nut to your friends, but also, anyone who tries to make it any of their business is being weird.
So you have something you enjoy when other people aren't there? Great. Enjoy it. And don't let other people mess with your head.