Hi Windy> I took an excerpt from Internet..
Concept: According to the theory, male (Y) sperm are faster but more fragile than female (X) sperm. Further, acidic environments harm Y sperm, according to the theory, making conception of a girl more likely[2][page needed]. The Shettles method aims to exploit these two factors.
Timing of Intercourse: In order to have a boy insemination should occur as close as possible to the moment of ovulation so that the faster, Y-sperm arrive first and achieve conception, according to the theory. When seeking a girl insemination the couple should seek to have sex 2½ to 3 days before ovulation.
Sexual Position: Shallow penetration coupled with the sperm deposited close to the entrance favors female conception because the area is more acidic, which inhibits the weaker Y sperm, according to the theory. To allow the Y sperm to reach the egg first (which supposedly moves at a faster rate), deeper penetration should be sought, to deposit the sperm at the least acidic area near the uterus opening.
Why is everyone guessing you are having a boy? Any reason?