I have always felt as though I was given the wrong name. I don’t feel like a Barbara. I never have.
I think we should all have naming ceremonies as adults, and we should get to pick our own. You should have a birth name and a real name. Mine would be Serenity. But the way the culture is at present, if I tried to change it now, I’d be laughed at by everyone who knows me. I am resigned to my name.
Even better, our names should be our story. They should be added to with each passing year based on our traits and experiences. By the time we are 80, our full names should take hours to recite.
For example, You would have “Mary, who danced before she walked, who loves dogs, who shocked everyone by spelling O U T at age 2, who was Rudolph in her Christmas pageant…” And so on, and so forth.
In a world like that, if someone said, “Tell me your name,” they would be indicating that they really wanted to know you well, and they’d settle in for the duration with a nice cup of tea. And telling your name would be a gift that you would only bestow upon those who you felt deserved to know the very core of you.
And after telling your story, you could say something like, “But call me Serenity, for short.”
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The View from a Drawbridge 
Always wondered why more people didn’t name themselves. I went thru the full process at 22, and thank whatever that acquiring my online nick was a lot simpler. That’s part of why folks don’t do it, I guess, but also a lot of them don’t think it out and realize that they can.
Maybe you could use Serenity as your middle name. As to idiots who laugh at others, for whatever, I don’t know of a non-serene way to straighten them out. You’d think grown-ups would know better.
That feeling that something doesn’t fit must be what transsexual people go thru. I’d consider a sex change if anyone ever comes up with one I like…
Mix and match? Why not! But yeah, I had my middle name legally changed to my husband’s last name, and what a hassle. I actually had to appear in court, and it cost a fortune. But it was a nice gift of connectedness that I would do again in a heartbeat. Serenity will just have to be my soul name, I suppose.