Is there a way to... (A little TMI!)

Is there a way to make sure sperm actually stays inside of me after me and my fiancé have sex? We're trying to conceive and I'm just trying to think of a way that it won't keep messing up my underwear!
​I thought maybe a tampon, but my fiancé pointed out that might just absorb it.
​Any ideas or tips?! I want it all to stay inside so I have a better chance of getting it to where it's supposed to be in my body! Don't want to waste the baby makers!