@Domi0205 - I'm not a T1, so have no experience of using insulin to share. However, I have done a lot of reading, and as a former anorexic, I do understand the body battles our mind puts us through when it comes to body shape, weight or whatever it is that drives you.
My understanding of insulin is it will only cause weight gain where the balance between insulin taken and food eaten isn't well matched. An exception can be when recovering from DKA, due to the body's natural need to recover a healtheier state.
Four months is a very long time indeed to not have taken insulin. Do you take any at all, like your long acting, and "just" skip the short acting, or do you ignore the whole thing?
I don't want to talk specific numbers with you, but it is important that you seek help for this, but also that you try to make a pact with yourself to start doing at least one thing to improve your health.
I don't know what ranges your clinic expect you to work within, but if you aren't taking insulin, I imagine those numbers and what your meter would say aren't going to be in anyway similar. I think sometimes in those circumstances, it seems like a massive hill to climb to move from where we find ourselves now, to where we really should be for a healthier life, so don't set that as an immediate goal.
How about setting a goal to start testing, at least once a day, and injecting your insulin more regularly. Then, scary though it may be, you will know your situation, but more importantly, when taking your insulin, and seeing the numbers coming down a bit, you will have successes to log and celebrate (even if it's inwardly). Positive successes are important.
Do you talk to your folks about this, and if so, what do they say? Are they concerned about you, or do you hide this from them too? Eating disorders can turn us into sneaky people. I know.
Domi0205 - There are plenty prople out there who will try to help you, and by coming on here and posting, it shows you recognise where you are and what you're doing isn't the best way forward. Build on that.
I know my eating disorder was very different to yours, but I got myself to death's door (literally) before I didn't anything about it. Stubborn? Me? You bet your life. I was ill enough that my parents flew out to say goodbye to me (I was living overseas at the time).
I don't say any of this to say "I was more ill than you, so there!), but more to help you understand that your position isn't hopeless. You can get better and you can go on to build a successful, productive life for yourself, the the challenge and the answer is in the first step.
Really, really good luck with it all. You deserve a much better life than the one you are currently walking towards.