Kate... Just to let you know that obstaining for too long (more than 4 days) can increase your chances of a girl. And this had been proven with a study.
When using the O+12 method (for a girl) they recommend obstaining (I can't remember for how long) before you have your one shot attempt.

So there you are you attempt may have been more suited to a girl

Tanya
Oh and BTW, I have that book that Nickers recommended, if you would like to borrow it for as long as you need