Belle is right, if you have normal sized fish in the tank they will pray on babies and only a few would make it to adulthood. Shrimp also arent like the common snail, you wont one day see 100 babies swimming around.
They take time to have babies and they dont breed like rabbits. Also if you gain to many shrimp for your liking you will always be able to sell the ones you have. People love buying shrimp. Trying to get female only shrimps might be tough, shops dont like to have to hunt for certain shrimps and if they are young enough its hard to tell them apart.
Take a chance and get some more without caring about sex. Youll actually fall in love with watching a buried mother. They take great care of their eggs and its so fun to see the progression.