LOL its funny I sort of think of the same thing with me.. I have 2 girls.. never had any boys and I think omg I wouldn't know what to do if I ever had a boy!! I pray I don't end up taking him out in pig tails or anything if I ever do have a boy!! lmao!
But as to Evie I would say you are doing the best thing you can do to suport her.. just have an open comunication line between the two of you. If it is "girl" issues that upset her then you being another female will be a comfort to her as someone to turn to for advice and understanding. I would think that growing up with lots of brothers might make girl issues harder for her to work out then say if someone was bullying her or something that she could respond to as she would if it was her brother doing it.