How do you know your family is complete

My husband and I have 6 and 3 yr old boys. Everyone has asked if we will have another one. That question doesn't bother us.

My husband and I go back and forth. When I look at our family in general I feel like there is someone missing. It also kinda hurts to say we are done.

My husband says he wants a little girl but he want the world to get better its too crazy. However we are both 35 and I feel like it's now or never.

I don't know if this is baby fever and it will pass or something else.