Self harming is no joke, if you're therapist, (T) thinks that it's not a big deal, I would suggest reconsidering seeing that one, and getting another. You're dissociative, which by itself can be dangerous (you're not fully conscious to deal with potential threats in your environment) and your self harming, which could lead you to hitting a major artery.
I used to Self harm along time ago, but I grew out of it, (or I got better at dissociating whatever came first! :) ) be careful Kayleigh, Self-harm during these dissociative states are ESPECIALLY dangerous because you're only partially conscious when you engage in these acts; god forbid, but what if you were to hit a major artery by yourself? Our bodies have many major arteries in our legs, arms, necks, heads, spines, etc.
If I were you, and I know this sounds like a stretch, but I would throw out/ give up all my sharp utensils and get plastic/disposable ones so that way if you do get the urge to cut, you can throw them out. Locking sharp things away doesn't really help unless you've really developed the self-control to abstain from self-harm, and that can take a while.
Anyway, you need to talk to perhaps your parents, or someone who you really trust, who can help you get help for this; by understanding dissociation and your reasons for self-harming, you can begin to effectively manage your triggers for self harm. I can only say through experience that alot of people who dissociate, self-harm to release intense emotions, and to feel 'real' and to ground themselves when they enter dissociative states; sometimes I've done it during dissociation to protect my mind from the knowledge of my self-harming behaviors; it's like self-negation. either way, you don't want to carry this around alone...do yourself a favor and don't let this get the better of you.