The Breeder should always be your first contact, assuming you used a reputable one they will take the puppy back.
ALWAYS go back to the breeder first! You may not get all (or any) of your money back, but a good breeder will certainly accept your dog back and makes sure she is re-homed properly.
Why can you not expect all of your money back?
a) your puppy is now older - that makes her more difficult to sell
b) your puppy has learned behaviours in you home which may not suit another owner - that makes her more difficult to sell
c) your puppy may have to be kept separate from the breeder's other dog/dogs - that means she is costing the breeder money
d) your puppy may have to be advertised - again, this may incur a cost
e) your puppy's paperwork will have to be transferred - there is always a fee for this
However, any loving owner would put the welfare of the puppy ahead of their pocket and be prepared to take the hit. After all, YOU are the ones who have changed your circumstances - you haven't had the puppy very long - you obviously didn't think your dog ownership through.
If the breeder can't/won't take her, then go to a rescue. They will be better placed to ensure that she gets a good permanent home.
Personally, I would never pass on a dog or cat of ANY age without knowing EXACTLY where they were going and how and where they would be living. There are too many people breeding indiscriminately these days, or taking on animals on a whim and just passing them on when they get fed up etc. This leads to terrified, confused animals being passed from hand to hand.
That aside you could get a dog walker every day term time only. There is also doggy daycare.
You could use the option above if you really want to keep your puppy. I suspect you have just realised that a baby animal is just as much hard work as a baby human, and are regretting getting her. I hope I'm wrong, but I know that I would go to any lengths to keep my dogs within my family - they sre family.