Does the Shettles method actually work?
It may shift the odds by a percentage point or two. But sure, if you want to try it (and will not be devastated if it doesn't work ....) go for it. You might end up with a girl. Or a boy.
No. It changes your chances by a mere fraction of a percentage point at most. If you are not ready to accept either sex, you are not ready to be a parent.
No so-called "method" for choosing the sex of your baby is anywhere near guaranteed. Such methods might make a few percentage points of difference, but you would have to have a hundred babies or more to get any meaningful statistical results! In round terms, in a small family of two or three children (or even a large family of 5 or 6), there is nothing that you can do to significantly change the odds from 50/50 as to the sex of your babies.