Need some proper advice on how to correctly raise this teacup chihuahua.?

I was given a "8 week old " teacup chihuahua and I was feeding 3 times a day with the food that the Breeder told me to give her. I was took her to the vet the next day and the vet told me that she WASNT "8 weeks" she was 5 weeks! So I should be bottle feeding her because she wasn t supposed to be off her mom just yet. I know she needs to be with her mom but the breeder isn t a very good breeder and I don t wanna make things worse for her.. so how can I properly take care of this little one? I don t know much about little puppies, she is my 1st one. I really care for her and I wanna do this correctly. The vet also gave me some puppy food and told me that I should be adding water to make us softe for her... I m a little un clear what to do... someone have any advice???