Thank you for posting. It does sound like classic symptoms. I am personally familiar with the depression part. Cutting is just a symptom of severe depression. Most people don't understand it. It sounds ludicrous to normal people, who have no desire to cut themselves and have difficulty imagining how anyone could actually want to do that to themselves. The people who will understand are other patients who've been there themselves, and their psychiatrist doctors who treat these types of disorders, usually successfully.
I too was initially afraid to try medication. My doctor talked me into giving it a try. I tried a whole lot of different medications and none of them really worked for me, but we kept trying, and one day we tried another and I quickly could tell we had found a winner. Life just slowly got better and better. Full recovery took a whole year. Now I'm pretty much symptom free and don't really think about it anymore. The only time I think about it is if I stop taking my medication, then after a few days or weeks I'll go downhill again, and I'll keep sliding downhill until it gets really bad again. I can turn it around by restarting my medication. Then I slowly get better again.
The medication doesn't make me happy. It just fixes me so I can be happy.
I asked my psychiatrist doctor why antidepressant medications now have a "black box" warning that patients may kill themselves. Well duh, they're super depressed and suicidal. I get that. But the black box warning seems to indicate the medication itself might cause someone to become suicidal. My doctor says he's never encountered a medication which actually caused someone to become suicidal. That would certainly be the opposite of what we hope the medication will do.
Another theory is that very depressed patients are too depressed to actually commit suicide, but once they get on an antidepressant medication it lifts them up out of the depression just enough so they can actually act out the suicide, which they weren't able to actually do before the medication because they were too depressed. So key is to hang in there during the recovery period and keep hope that it's quite lilkely there's a medication out there that will help tremendously, but it takes time to work, the progress is slow, but keep it up and after a couple months you'll feel well enough to not have suicidal thoughts anymore, and you'll continue to get better and better over the next year.
I'm not as familiar with eating disorders. I've read one theory is we have a map of our bodies in our brain, and it might be that map of our body says our body is very fat, when in fact it's very thin. The brain's map of our body might not match up with our actual body. (People who lose a limb may have "phantom limb" syndrome, where the brain's body map still has a limb there even though their actual body no longer has that limb. It can work the other way too. A stroke can damage the brain's body map, erasing a limb. The patient will then no longer recognize the limb as belonging to them. They may ask the nurse to "Please take away this lunch tray I'm done eating; and please take away this limb that's not mine.")
The hopeful news is the brain is "pastic" meaning it can literally rewire itself. Thought exercises can literally heal the brain by forcing the brain to rewire itself. A brain body map that's too fat might possibly be shrunk simply by setting aside time each day to consciously think about shrinking the body map. By thinking about shrinking the body map, imagining the body map shrinking, one may be able to shrink the body map so it properly represents one's actual body more accurately.
There are two books on brain plasticity by Dr. Norman Doidge. (2007 and 2015). If you're interested you may have a look at those two books. (Chapter 1 of the 2015 book is especially useful.)
A psychiatrist is a doctor who specializes in treating these types of medical disorders. A good psychiatrist will be able to help you.
PTSD is also treatable. One tidbit of knowledge is "recalling a memory rewrites the memory." Memory recall isn't a "Read Only" thing. The brain actually "re-stores" the memory when you recall it. So the trick is to be in a calm relaxed state, then tell your story to someone who listens, and the story gets rewritten with a calmer emotion attached to it. The story itself of what happened doesn't change, but the emotional signifiance we attach to the story is changed and becomes less emotional. In this case one approach is Talk Therapy. We tell our story to someone else who listens, and that somehow rewrites the memory itself. (I've also read there's a blood pressure medication that can be used to enhance this treatment. Look in Smithsonian magazine for an article on PTSD from about 5 years ago.)
The other approach is to purposely forget the memory so it fades. Thinking a thought strengthens and reinforces that thought. Recalling a memory strengthens and reinforces that memory. If there's a memory we'd rather forget, we can consciously not think about it, and whenever we find ourselves thinking about it, we immediately force ourselves to switch to thinking about something else. (One way is to "return our focus to the present moment". This is the meditation approach.)
So I understand you have eating disorder, depression, and PTSD. Plus sleeping disorder which is probably just a side effect of all that.
So far it actually sounds common; that is, all the symptoms sound common. I don't mean that to belittle the problem. It's definitely a real and serious problem. I only want to convey if you were to tell a psychiatrist doctor all these symptoms they would immediately recognize all of them as the type of symptoms they commonly deal with. I'm a patient and I recognize all of the symptoms described as ones I've either had myself or I've read about.
I'll end with a link to a story that may be of further help:
The last bit of suggesetion I can give, to help deal with feelings of isolation, is Google "Conversation Starters" and memorize them. (Some places call this a "Question Bank". A list of questions one can use to help facilitate a conversation. I've been studying them myself and have noticed some success with them. I'm still no expert, but I keep studying. I also now notice when others are using Question Bank questions on me to help make a conversation go.)
Best wishes. I hope some of this helps.