Don't let them get to you, Marie, as I truely believe your friends didn't mean to be so insensitive.
They are so wound up in their world of motherhood, or future motherhood, that they neither try, nor want to see where you're coming from.
It must be difficult having so many friends with young kids, and noone to relate to. I agree with Kim, explain to them your feelings, and if they are good friends they will accept you for who you are.
It really is ignorance, and if they are all on the same page re the kids issue, then they will be enjoying being one of the pack, and also enjoy trying to change your opinion. ( what better confirmation for them that their lifestyle choice on having kids is the right path, when all their friends agree and are doing the same.)
It will seem even more strange to them then that you disagree.
For the less secure of your friends it will also throw into question their life choice, as though you are saying ' hey, there's a better world out there that just having kids ' and those people may want to attack that.
I was reading an article on marriage, ( basically saying to expect the love to last for a lifetime these days is outdated, and many live in unhappy partnerships because of financial constraints. quoting also the number of divorces )
afterwards people could comment....one of the comments ;
'
'Marriage for most people is about kids and family. I am sorry, but couples with no family responsability are only really in a psuedo-marriage. let them be in civil partnerships, or whatever they want to call them, but best leave marriage to the grown ups.'
you can imagine some of the replies - a few from people who are unable to have kids - but alot stated the ignorance in the comment.
the trouble is, there are many others who completely agree with these sentiments, and the trick is not to be around them.
I too found it easier once I got past 40 - not that i'm wishing your life away

but remember there are many others like you out there, going through the same thing. it's good to talk.
plus, here of course ! always good to vent.
plus, don't cry. it makes your skin puffy