I think you need to strike a balance between the two different styles. So for instance go for a name that is well known like 'Katie' but unusual like 'Acacia' thus you can find a perfect choice that fits both your styles, with you having the ultimate say obviously (; However I can understand that you may hate nicknames, but nicknames may simply come naturally. For instance I have a friend called Katie and everyone calls her 'Flo' or 'Unicorn' this has nothing to do with her name but her arty attitude. You may never be able to escape a middle name. Nevertheless, I'm Victoria and I've only been 'Vicky' for a short spat and apart from that period I'm normally just Victoria. Sometimes I get Vee if my family are being lazy or Toya if the little ones can't say my name, but aside from that I'm proof that you can go with Alexandra and not necessarily be Alex.
Elinor, Evelyn, Vivian, Willa, Edith, Mary, Rachel, Sallie, Allison, Amelia, Daphne, Mara, Johanna, Nina, Margot