To wait or not to wait

My husband and I currently have an 18 month old. I’m a law student and he’s in law enforcement. We decided to start our family “early” as our parents had us later in life. We both have a brother his is 10 years older than him and mine is 20 years older than me. We’ve known since day 1 that an age gap that great wasn’t what we wanted. Our daughter is our world. I worry that I won’t be able to love someone else as much as I love her ( I know that will change with number two but it is a concern of mine). I have done extensive research and I have found that there isn’t a perfect” age gap. How far apart are your kids? Do you think it’s ideal or would you have preferred them closer or farther apart?