should i have another baby

I am 40 years old and already have 5 children. My boys are 17 and 14 and my girls are 10, 7, and 2 but I feel like there is something missing. I want another baby and have always wanted a large family, but I look at my older two and think am I too old to do this again. Friends and family tell me to be blessed with what I have and that I am too old to go through it again, but I feel children are a precious gift of god and if I am blessed enough to be able to have children I will only be given what god thinks I can handle. I would like to have some opinions from others as well as advice that I can take in and pray over and make the right decision for my family.