goodness. no one is treating you differently here because of your age. but perhaps from your teenage perspective, you can't see that? I think it is a gross stereotype that simply because we are adults we must have NO idea where you're coming from.
calm down.

yes, of course it could be DID. but you know that already. but yes, there are other things it could be - bipolar, schizophrenia, borderline personality disorder... no, they may not seem as likely (especially now that you have clarified some of your symptoms), but they are possible. my husband is bipolar and even he has described having alter egos that he will refer to by other names or nicknames. he also lacks a lot of memories from his childhood. but no, he does not have DID.

there is a reason that many people with DID are commonly misdiagnosed as having some of these other disorders before a diagnosis is reached - they all have a lot in common. it wouldn't hurt to take a look at the information about them and see if any of it relates to your situation. it may help you feel more sure of what your dealing with so that you are more able to accurately describe to a doctor what is going on and be able to reach a correct diagnosis sooner.

and for what it's worth, I do understand where you are coming from. I remember being 14 and it sucked. I was also suicidal at that age. and I ran away from home when I was 14. I also happened to be in therapy around that age, but since it was also family therapy it really did me no good because i did not feel comfortable opening up to a therapist that the rest of my family was talking with as well.

you may want to keep in mind when you do seek help that ALL doctors will have to take into account your age as they are trying to help figure out what is going on with you. just as they would for EVERYONE else. not just other teenagers. you might try to relax about that a little. even i have to wonder sometimes 'are these awful mood swings this week because of my mental health problems? or is my period almost here? maybe I just have PMS.' that's part of being a woman. keep in mind that your mental health and physical health are all intertwined. they're not always separate.

you might try keeping a symptom journal (if you don't already) and tracking things like mood swings, headaches, lost time... all those things. that would be very beneficial to you when you see a doctor.

take care.