i feel the undiagnosed part my only advice is to find things that are easy to eat and stay hydrated! eating cool foods is easier to me when im feeling nausea due to hunger (english is my second language, so lmk if anything sounds confusing)

This moreso sounds like disordered/unhealthy eating. You don't need to be diagnosed with an ED to know you have one, but there's still a difference between each of these things. Eating disorders, such as anorexia or atypical anorexia, are purposeful and conscious actions. It's not a healthy mindset to be in in the least, and many (not all) strive towards as low a weight as possible. Now with this said, if you're struggling with your intake and appetite you should still try and find help so it doesn't impact your overall health! I don't have much advice on how to get more of an appetite, but I do recommend that for what you can manage to eat that you consume more calorie dense foods/vegetables so you can try and reach more of your nutritional needs. But I'd certainly recommend a doctor or nutritionist!