I think if you want your own invitation you should move into a separate household and then it won't be an issue. I don't care what the new rule is - one invitation per household is fine IMO. It seems silly to have the postal service delivering all these separate envelopes to the same address.
At 21, I think you need to learn to understand that you are probably not considered an independent adult yet by your relatives. That's just the way it is. I lived in a different state from my parents, but it probably took until I was about 24 or 25 for me to get separate invitations, Christmas cards, etc. from family members. Not so surprisingly that was about the time I'd gotten a track record of communicating with them on my own and not through my parents - calling or visiting them, sending them greeting cards, etc.
At 21, I think you need to learn to understand that you are probably not considered an independent adult yet by your relatives. That's just the way it is. I lived in a different state from my parents, but it probably took until I was about 24 or 25 for me to get separate invitations, Christmas cards, etc. from family members. Not so surprisingly that was about the time I'd gotten a track record of communicating with them on my own and not through my parents - calling or visiting them, sending them greeting cards, etc.

ing a little!
You will learn later in life, that this was a very small blip on the radar and hopefully will see the error of your ways. If I were you, I would let this thread slip away. You were wrong, plain and simple, to correct your aunt. If I were you I would be making amends with my aunt instead of defending your behavior to a bunch of strangers who really don't care, myself included. If my niece had called to "politely" correct me, I guarantee you by my response she would never ever be doing that again and I would be expecting a full apology.
And she'd probably be in charge of all future invitation addressing tasks so they would be completed to her high standards.
I can't tell you how mad I would be if my neice did to me what you did to your aunt.