Masturbating releases more hormones that may increase sexual arousal. Masturbating is not a good technique to reduce sexual desire. It usually increases sexual desire.
Also stop feeling ashamed. There's nothing wrong with touching your own body and enjoying how it feels. It's your own body!!!! You are allowed to touch it!!!! Almost everybody masturbates. There's no reason to be ashamed, especially when you are doing it in private and no one knows you did it anyway.
So what can you do?
-stop feeling ashamed and accept your body and accept that it's okay to touch your own body
-if you don't want to feel aroused, you may want to try not masturbating at all
-if you start feeling aroused or want to touch yourself, go for a walk or bike ride, go to the mall, hang out with friends, go run some errands - just something so that you don't have the option to touch yourself
-if you want to keep masturbating (perfectly fine), maybe try switching it up and trying different methods - order a sex toy online (discreet shipping), watch porn, lie down in a different position than you normally would, etc
-accept that sex isn't everything, and you don't need it to be happy right now, it's not always all it's cracked up to be
-realize that one day soon you will have a partner/relationship and won't have to be sexually frustrated anymore - this is only temporary