Do you feel theres a time window when having another child?

Undecided if I want a 3rd child. I already have a boy and a girl, that's what I always wanted but I can't help but think what if I'm meant to have another one??How did you guys decide you were done? One day I think to myself, yeah I can do another one, and the next I'm like no. Lol. However I feel like if I don't get pregnant by the time my youngest is in school which is this fall, i should be done because Im out of the baby phase. Idk, tell me your thoughts!