This is a subject of endless debate on every relevant board or site I've visited.
I understand the power of words and desire to put a positive spin on things. Perhaps childLESS does sound a little pathetic or forlorn (and if there's one thing I hate, it's being the object of pity). I may be "less" or lacking a child, but I don't believe that means my life is any less interesting or valuable or valid than a parent's. It's just different.
But to me, childFREE isn't quite right either, because it implies that we are happy to be "free" of children, as though we consider them a burden, when nothing could be further from the truth. It does not reflect the battle we went through to try to have a very much wanted child, or our struggle in trying to decide when enough was enough and when we should stop treatment, or the struggle we've had to find new meaning in our life since then. If I am FREE of anything, it is the burden of infertility treatment!!
The term childFREE is also widely used by people who do not want to have children, & I think it creates a lot of confusion in the eyes of the fertile community. Some childfree by choice sites can be extremely anti-child. Nevertheless, I do enjoy visiting some of them. We have a lot in common, in the way we are viewed by society & the situations we find ourselves in (including having to explain and sometimes defend ourselves) -- and the women (& men) on these sites are extremely clear about the advantages of not having children. Sometimes, that's a message we need to hear!
One of the best such sites/blogs I've found is Purple Women -- lots of thoughtful, reasoned commentary on living without children (albeit by choice) in a world geared to parents & kids. I'm not sure I can call myself a "Purple Woman" by their definition. Lavender, perhaps?? Anyway, my solution, until something better comes along, is usually to use the term "childless/(slash) free" in my writing.
And of course, I am actually not childless/free at all. I am a mother -- Katie's mother -- but that's another post for another day...