Well, ideally ethnicity shouldn't
matter (especially to a 13 yr. old), but certain people around you are forcing you to have to navigate this issue. All those racially-based comments come from others'
racial fixation and racial confusion. And unless you're a robot, of course you're going to feel the effects of it at times. So have some compassion for yourself for having to deal with everyone else's crap!
You can learn to make some peace with this by practicing patience toward others and yourself re: issues of "race". That doesn't mean you habitually let folks off the hook for hurtful comments. But you may want to pick your battles or you could burn out
Their comments aren't as personal as you might think btw. To explain:
Society is generally conflicted about race and many people try and feel safe by putting others in a "box" called "White", "Black" or "Asian", etc. Some reasons for this: to try and predict what they can/can't say or do, or to keep you at a distance based on stereotypes. When you don't fit neatly into one box, it can heighten their anxiety. Some ppl - a common theme in my own life - want to know "what you are" to guard against being discriminated against themselves
Those dark-skinned jokes could be their internalized racism. Colorism - that tendency for non-white communities to exalt the pale skin associated with whites, is a vestige of Colonialism and I won't depress you with details, but you might want to research it for you own understanding.
Often ppl are just genuinely curious about your background because they find your look interesting/pleasing and wonder if they've accurately guessed your ethnic background correctly.
You know what you are, ethnically. It's reflected in your parents. Society's confusion has confused you at times, understandably. If someone wants you to "claim" one thing, that's their confusion and insecurity speaking. You don't owe any one group or person anything. You are a unique human who also happens to be living a multiracial experience. We all are unique, we all have hangups and we all impose those hangups on others at times. No one is better or worse than anyone else.