Keep in mind that you can't invite everyone.
Last year my then 9 yr old was the flower girl in my friend/coworkers wedding. She also had no kids invited to the wedding besides her and the ring bearer. I assumed that meant my then 16 yr old wasn't invited as well and never asked. When I received the invitation in the mail it was addressed to myself and both of my daughters. When I got to work I thanked her for including my eldest and her reply was "Oh, London is not a child, she's 16! Plus how would it look if I have her baby sister in the wedding but not invite her?"
My niece of my older sister got married two months ago. BIG formal wedding, well over 200 guest. However, I knew how my niece felt about having kids attending her wedding. She didn't even have a flower girl or ring bearer herself, she did however have two Jr bridesmaids but I believe the ages of both of the girls were 15. My two daughters who are her first cousins and they are very close to their big cousin. I'm the youngest of 5 kids myself and there are huge age gaps between myself and my older sisters, even the sister who is closest to me in age and the mum of my niece who is of marrying age mine aren't, they are now 17 & 10. I knew my eldest was invited to the wedding however I wasn't sure of the bridal shower and in the case of the youngest I wasn't even sure she was invited to the wedding. My niece came back to me personally and said "Auntie, how could I get married and not have London and Lizzy not be there? What I meant was I wanted no little children, Lizzy is 10 and a big girl. Even Mike(now hubby) wants Lizzy there."
So, my eldest daughter and I attended the bridal shower and my youngest wasn't upset about it in the least. However, it would have crushed her if she couldn't come to the wedding so I'm glad all three of us were able to attend. So even though she was family and we all are very close I never assumed that my kids were invited.