I have a soft spot in my heart for Harriet as it's my great-aunt's name. She's one cool lady. Goes by "Hat." "Aunt Hat." I know it really feels like an old lady name, but honestly when I think of it on a little girl, I just see my Aunt Hat in little girl form...pixie haircut, spunky sweet little thing in a sundress.
I think Hazel nn Hattie is solid :).
I like Hazel, nn Hattie. I don't think it's a problem for it to be a bit of a stretch. I mean, aren't many nicknames like that? Maggie for Margaret or Callie for Caroline aren't exact matches either, but people have been using them happily for years. Besides, you'll just introduce your child by what you want her to be called and most people won't question it.
Heather (this might result in Hetty also)
Athena/Artemis (bit of a stretch but could work)
Not sure if you're religious at all but Hadassah is the Jewish name of Esther in the Bible. Haddie from that would definitely work.
Hadiya is a lovely Arabic name.
Hmm. I like Haddie for Hadley...if you used Hazel, how would you feel about Hazy as a nickname? That could be super cute.
My favourite is Harriet!
I think even though people are suggesting names it doesn't automatically much up with the nickname. I mean would you automatically associate the nickname Hattie with Hayley? As honestly I wouldn't. In the UK where I'm from nicknames as names like Evie, Ellie, Alfie and Charlie are really popular. Hattie would defiantly work as a name in her own right. I know in America this isn't a popular craze but then that would make her name unusual but not crazy. I would embrace Hattie as a first name in her own right :)
My advice to you: if you can't find a full name you love as much as Hattie then just go with Hattie. While I like Harriet, I prefer the vintage Hattie much more. Hattie is one of the few nicknames I don't mind as a given name. Hattie Beatrice has a lot of old-fashioned charm.
I'm in the straight Hattie Beatrix camp, if you can't be persuaded to go with Harriet. Otherwise, here are some thoughts:
Any H first name, plus a D middle to get to Haddie. (reminiscent of the poet H.D., whose real name was Hilda Doolittle)
Or a T name, for Hattie
Just name her Hattie! It is a fine name, no less grown up sounding than a lot of "ie" names being used. I would not settle on a name just because it gets me to Hattie --just make it her name. I do think hazel to Hattie is a stretch, but it doesn't make much sense to me, either. How annoying for her (as hazel) to be called Hattie her while life, from day one, but she has to carry around the name hazel? It might make sense if you planned to use both names interchangeably, but that doesn't make sense to me either, because they aren't related. If you can't see yourself naming her Hattie, I would name her Beatrice Hattie and call her by her middle name. But again, it may make more sense to just name he Hattie from the beginning. Hattie Beatrice is charming!