Have you tried contacting the breeder?
What does your contact state, a lot of breeder contracts state that the pup must be seen by a Vet within 72 hours of you taking possession of the pup?
Where did you go with your pup when you first got it, where did you put it down to go potty?
There is an outside chance that your put picked up Parvo the day you picked it up. There is a 3-7 day incubation period before the puppy seems obviously ill.
See this LInk:
http://www.marvistavet.com/html/canine_parvovirus.html
You picked up your pup on April 11th at 10:00 am.
The pup became sick on the 14th a night.
So there is an outside chance that the pup contracted the Parvo when you got her, there is a chance that she had it when you got her.
Unless there is a real clear cut time line, if there is a doubt one way or the other, the odds of winning in court in my opinion are not that great. As long as there is research that says "There is a 3-7 day incubation period before the puppy seems obviously ill." the court may not rule in your favor.
I am really sorry that Angel got Parvo, but maybe I am looking at this a bit different that some, honestly the pup could have gotten at the breeder or it could have come into contact with the virus while in your possession.
If you go to court you can have a statement from your Vet and the breeder will have a statement from her Vet and supporting ducumentation that the pup could have contracted the Parvo after it left her place. So a Judge is going to have no clear evidence that the breeder is at fault.
I hope Angel is doing better.