I appologize for butting in, but...
A perspective comming from a male point of view..
1. It is your wedding, and you should do what ever makes the day most special to you. For most people, there is only one wedding day. So invite who you want and don't invite others.
2. I have been at weddings where children of any age (infancy to teen) caused so much comotion and made the wedding and reception not at all that enjoyable. Crying infants that the parents refuse to leave the room with, and children and teens who just create an unpleasant enviornment. I've also been to weddings where the children were well behaved. Really it is up to the parents of children no matter what the age to see that they behave and do not become the center of attention. The bride a groom should be the center of attention.
3. If someone says they cannot come unless they can bring their newborn, or 8-month old or what-ever, ask them nicely to please try to find a sitter for just this once.
4. If you are as important to your friends, as you feel they are to you, I believe they will understand and respect your wishes. The ones who feel you are an important part of their lives will make arrangemens, the others will not.
In the end, it all comes down to number 4 doesn't it?
Congratulations, and I hope you have a very special day! And a wonderful life together!
Just MHO, YMMV