I have never been able to bring myself to self harm with metal, only my fingernails. I typically don't self harm in general, only when I am deeply frustrated or feeling aggressive and end up turning that inwards - has to get out somehow or I get that 'crazed' feeling at not utilizing an outlet. Forveleth has good questions that should be helpful.
It can be satisfying doing a substantial amount of damage but physically it often doesn't hold up as well. Maybe it's because of the desire to do a singular deep cut, the intent may be putting you off subconsciously? I wouldn't worry about staying silent or not, that's like torture. If you're worried about them hearing, just wait until they can't. Or just stay with what you're familiar with. If it helps, it helps, no real need to try something new. I only do self-harm to soothe my emotions to heal, as the festering emotions from lack of soothing do more damage than skin that heals on its own. I can't advise further but I hope you feel better soon.
