More kids?

I'm 33 year old my husband is 35. We have 3 boys. 15 year old, 7 year old and 15 month old. We recently thought I was pregnant. I'm currently on the mini pill. Missed a couple of pills 4th of July weekend

Our 8 year anniversary. I feel like I want to try for a girl but I just don't know. How did you know you were really done?