Try any of these. Also your best option maybe be going to the pound or humance society and looking for a mixed breed of dog that is around the size you want and give it that loving home it wants. But here's some breeds that are aroundish 5 pds. Good luck and God Bless!
Affenpinscher
Australian Silky Terrier
Australian Terrier
Bichon Frisé
Bolognese
Boston Terrier
Cavalier King Charles Spaniel
Chihuahua (Long Coat)
Chihuahua (Smooth Coat)
Chinese Crested Dog
Coton de Tulear
Dachshund/Miniature Dachshund
English Toy Terrier (Black & Tan)
Griffon Bruxellois
Havanese
Italian Greyhound
Japanese Chin
King Charles Spaniel
Löwchen (Little Lion Dog)
Maltese
Miniature Pinscher
Miniature Poodle
Papillon
Pekingese
Pomeranian
Pug
Russian Toy Terrier
Shih Tzu
Toy Fox Terrier
Toy Manchester Terrier
Toy Poodle
Yorkshire Terrier
Affenpinscher
Australian Silky Terrier
Australian Terrier
Bichon Frisé
Bolognese
Boston Terrier
Cavalier King Charles Spaniel
Chihuahua (Long Coat)
Chihuahua (Smooth Coat)
Chinese Crested Dog
Coton de Tulear
Dachshund/Miniature Dachshund
English Toy Terrier (Black & Tan)
Griffon Bruxellois
Havanese
Italian Greyhound
Japanese Chin
King Charles Spaniel
Löwchen (Little Lion Dog)
Maltese
Miniature Pinscher
Miniature Poodle
Papillon
Pekingese
Pomeranian
Pug
Russian Toy Terrier
Shih Tzu
Toy Fox Terrier
Toy Manchester Terrier
Toy Poodle
Yorkshire Terrier