I don't think that it sounds unreasonable at all, good on you for sticking to your guns.
Your DD sounds very much like my DS (15) who will quite happily take advantage of my soft disposition. I have had to crack down and get a lot harder on him.
I don't think it is unfair to ask them to help around the house in fact I think as parent we do them an injustice if we don't...they need to learn that not everything is automatically done for them.