some people are just so bored, they have nothing better to do than to be mean. it's sad that their lives are so horrible, they feel the need to bring others down as well.
don't sweat it. a LOT of people use the term "teacup" just because that is such a popular word and they don't know any better. maybe you could put a section on there that explains that you do not care for the term "teacup" but chose to use it because so many people "relate" to that word. but honestly, I don't think you have done anything wrong.
Whoever is sending you those pm's needs to concentrate their time on people who are "mass producing" dogs and not caring for their animals properly. I would gladly give them the address of a few places around here