"I have few friends."
Translation:Mam mało przyjaciół.
That's the problem with English, because 'a few' and 'few' look almost identical but mean quite different things. So as mihxal already said, "kilka" = "a few". "Few" itself has the meaning that it's too little, but "kilku" seems like quite an okay number of friends.
Conclusion: as the original sentence has "few", you need to complain about the number of friends here ;)