As a person who has lived with cats almost her entire life and at the moment has four cats at home (2 being siblings we got from a friend and the other two are strays from the neighborhood) I can tell you, you have a good heart and a kind soul for taking care of and bringing in these strays into your home. Bless you for putting another creature's needs before your own. Taking that kitten to the vet was the best thing you could have done. If you can, continue taking care of these cats as best as you can, because honestly, not many people will choose to do so.