Trying again since my prior got deleted for "seeming fakeclaimy":
Hi there, I'm a social worker, and I want to reassure you that it's all right to feel different things and be unsure of your exact identity at this time, especially if you're younger. Things can feel very intense and confusing as you learn you who are. Having changing moods, interests, even gender and name, can be part of growing and developing into your full self. Some people know very early exactly who they are and every part of their identity, but it takes awhile for others.
You say that you aren't an actual system, and that's okay, too; feeling like multiple people doesn't necessarily mean you are multiple people.
If the inconsistent ways you're feeling are causing you a lot of stress, it may help to talk to someone on an ongoing basis who can help you identify and understand why in a way that an online message can't.