Am I ready?

How did you know if you were ready for another baby? This would be baby #3 for us. Me and my husband have seriously been considering trying. For about a week now it's all we talk about. We're financially stable, healthy, I'm 29 he is 33. We already have 5&7 year old girls. And they brought up wanting another sibling before me and my husband even considered anything. Everything is pointing for us to do it but I worry me or him will change our minds later on and I don't wanna find out I'm pregnant and that happen. I've never been this okay with the thought of having another baby though. I know we can do this and handle it. We both get excited about the possibility of another baby. I use to be sure I was done but now, idk. How did you know for sure you were ready? Does your mind change? Please tell me what you think?