There is a 51% chance of you having a boy, and a 49% chance of having a girl. It is the same for everyone. Statistically there are more male babies born than female. There’s really no tried and true method for giving birth to one or the other. Yes, the male sperm are faster swimmers, though they die sooner. While female sperm slower, they are more resilient. Now if you have sex a few days earlier (if you know when you’ll ovulate) you might increase the odds of having a girl though it’s still anyone’s guess.
The man chromosome are XY, if the sperms live inside of you for a while before ovulation, while the chromosome Y are weaker and die, the chromosome X will live much longer, so if you leave the sperm inside of you for a few days before ovulation, most of the chromosome will be X so you get a better chances of having a girl, if you do it on the same day your egg is released you will have more chances of having a boy because the chromosome Y is very strong on the day of the release of an egg. But in the end, it’s all 50/50.