you will find that it will tend to leak out when your not ovulating as your cervix is closed, when your ovulating with the help of fertile mucus the sperm can swim thru your cervix and it usually doesnt leak then
I've already commented on your other post in another forum.
There is sperm in the pre *** as well. Don't fret to much as it takes healthy couples up to a year to conceive. Since there is only a 20% chance to get pregnant every cycle. It's very unlikely that this is causing you to not conceive. Are you using an opk to track ovulation? As you might be missing you ovulation.