I have yet to know of a gender specific spell that works. Unfortunately, as of right now, gender is not something we get to determine.
There are some old wives' tale,s which vary from having sex two to three days before you ovulate, then abstaining the next four days (because female sperm swim slower than male sperm) to having your husband taking a HOT shower right before intercourse (because female sperm is more heat resistant than male sperm).
BUT, if I were going to attempt to do such a spell then I would have your husband participate in the spell because it's the semen which determines the sex of the baby.
13 Magickal Moons has a fantastic fertility spell kit which is super easy to do. Just modify the wording to specify a daughter.
Please let me know if you two finally have your little baby girl!