That's a pity, OP. Are you Home Educated because of the MH reasons you have been seeing CAHMS for? I'd suggest that you write down what you would want to say and keep it safe - that way, if you can't bring yourself to say the words, you could hand to somebody you trust, like your GP (you could post it or email it or stick it through their letterbox whilst you're taking the dog for a walk as long as you give your name, address and date of birth so they know it's you...)
If you like oats, then making porridge (or overnight oats, the only difference is that for this, you add the non dairy milk to the oats and then stick them in the fridge overnight) is healthy, satisfying and good for you - once it's hot, all you need to make something lovely is add as much nut butter as you want, maybe some yoghurt (coconut/soya) and then some syrup over the top. Maybe add bananas, berries or whatever you fancy at the time (Any left over peach and raspberry would be fantastic)? Adding cocoa powder into the soaking oats or some dairy free chocolate/chocolate coconut yoghurt (which is delicious) when the oats are hot?
I think you'll get the pleasure of having something that tastes sweet but without your energy levels crashing a short time later - which, when you are so hungry, is why you find it difficult to stop at one or two Oreos.
It's fine to eat a load of Oreos when you've been undereating for so long, don't get me wrong at all (and you're still undereating anyhow) - but you're more likely to feel sick and guilty with them than you are a lovely, lovely bowl of oats with all the flavours you like.
Chickpeas are brilliant. So are other beans and pulses. So are veggies, potatoes, fruit, rice, grains and nuts/seeds. Eat them, enjoy them. Enjoy the feeling of feeding your body so you are strong.
And if this all feels too difficult or overwhelming, please, please, try to tell somebody so you aren't carrying this on your own or by trying to get help from people who are so young, they are trying to find their own way as well.
You are not eating too much. But you are trying to take too much on your shoulders.
Let people who are more able to do it try and ease your burdens a little.