Am I wrong?

I been in a relationship for 13 years now. We have an almost 9 yr old together already. I been wanting another baby for the past 4 years now. I feel like I constantly talk about kids. All of my friends are on kid number 2,3 or 4. 3 years ago me and him talked Bout it and he say let's wait a year. Well here we are 3 to 4 years later still no kid.amd he know how bad I want another baby. My daughter literally cries for a sibling because she sees her friends at school with there little brother or sister or even when it come to me bringing her around friends with multiple kids. And she always ask how come I do t have a brother or sister. This makes me even more frustrated and sad. So with that being sad sometimes when he tries to have sex with me I back down and tell him no cause it's not like we are having sex to have another baby. We are in our 30s and I dont want to be that 40 year taking care of a 5 year old. I've explained this time and time. Is it wrong for me to not want to have sex because now I feel like I'm just someone to get a nut out of. Its depressing at this point. And I'm not the type to just go and cheat and have one by someone I dont know. I would rather leave and go to a clinic and see what can be done and have one on my own. Am I wrong for feeling this way.???