HELP: Dogs mating properly, yet no puppies despite SEVERAL attempts!

I have just started with dogs and have two. I just began noticing that the female is having a bunch of hearts  spontaneously and frequently. Is your female in heat? If so, have you matched your mating times with the heat cycle?

Update on that one... Since I was wondering if that was what was going on I just had my Sim tell the male once 'encourage to mate with...' and they did the noses and hearts thing you mentioned and ran off to play... and a couple of minutes later I have a notice that she is expecting puppies. Oh, man, and they have a new toddler... 😉   

So... maybe try to watch for her showing signs of 'heat', which is imperative for the process to work with dogs in real life, and still far from a guarantee.

By the way... if you're interested in the puppy experience and like Yorkies, I just saved and uploaded a copy of my household with the pregnant Yorkie under the name 'Chef with Pregnant Yorkie'. 

@KatieBBird2000, yes, @SheriGR is correct in that the pets have to be in heat for offspring to happen, and also that when you see hearts floating away from your pet (and sometimes it looks like the pet is singing!) that that is a sign of your pet being in heat! ❤️🐶🐱  There is no guarantee (especially depending on how full your household already is), but you can't get puppies or kitties in the game unless your current pet is in heat!  Now, the pets could still reject the other pet's advances, but I think there is an increased chance of a successful mating if they are in heat anyway.   I've had a dog have 4 puppies in-game, but you might have fewer if there aren't' enough "slots" for household members in the house you are playing! 😉

Happy Simming! 🥳