I see this as very common thinking among those of us who have problems. Our minds and emotions are at odds with one another with what we have learned or observed in our parents behavior growing up. I passed this on to my child as well, I think.I thought if only I could not be a sexual person, the panic would go away. I thought God was punishing me with panic attacks for how I would steal glances down their shirts when they leaned forward. I thought he was punishing me for, how to put this delicately, taking matters into my own hands.
This is my thinking and I don't know if it is normal or not, but it's different from how I used to beat myself up for what I consider natural, normal human emotions and desires. Your are wanting to be a non-sexual being, yet you were born with genitals and the hormones that become active at puberty to cause sexual desires and emotions. Taking matters into your own hands [lol], as you put it, is simply a normal desire and emotion resulting from those hormones. There's nothing wrong with you for having such thoughts and desires. You're normal. That is simply a normal part of maturing. I would suggest your Mother didn't handle the sex part very well. It's not something to be ashamed of, or try to deny that it's a part of life, but that sounds like how she tried to view and handle. I am guilty of the same behavior around my son. My behavior came from what is taught in the church. Some are better in knowing how to view it from scripture than others. I think to just not make it a big deal is the best way to handle it and understand that a kid at puberty and beyond is at times going to "take matters into his own hands." lol It's okay to be who we are, not what we are not [perfect and pure] but understand there is also a need for restraint or discipline. Balance.
I will say that I think that the better a child's need for intimacy and love are met, the less the child will feel a need to take matters into their own hands whether it is sexual, drugs, rebellion, or whatever.