This may not be what you want to hear, but hey. That never stopped me before.
Ancestors on my dad's side came here from Ireland in the late 1800s. Ancestors on my mom's side came from Scotland about the same time. Through the last century they married other immigrants and into various Indian tribes.
So here I am, at 50+ years old, a mix of European and native blood. I could probably be on multiple tribal rolls and get all the foofaraw that goes with it,, but it makes no difference to me.
Because I'm an American. That's all that counts.