You may find some of these things helpful for when the urges are strong. Sometimes writing and listening to music work when urges are more weak, but as they get stronger you need to do something to release that build up and energy. Maybe instead of the welting, try some things off
this list instead. You can match it to how you feel and what sensation you want when you self harm, and in doing that it may help to release the tension.
I recommend trying counselling, I know it;s scary but if your mum is willing to help out it is worth trying x