Done having kids?

How did you know you were done? I currently have a 19 month old son and am 21 weeks pregnant with our second son. When I found out that this one was a boy I was disappointed only because I had only ever seen myself having two kids, one boy and one girl. I have never wanted 3 kids and even if we did have 3 we would have to get a bigger house and a bigger vehicle. I’m 23 years old and after I have this baby I planned on getting an IUD and not do anything permanent like tubes tied or my husband have a vasectomy until I’m 30 just in case I change my mind. I’m concerned if we don’t try for a 3rd I’ll always wonder about a little girl, but if we do try and it’s another boy then that’s 3 boys! Don’t get me wrong I’d love all of them with everything I have but like I said I never imagined myself with 3 kids but have always seen myself with a daughter. Anyone else felt this way or gone through this?