One Little Heartbeat

I had an ultrasound yesterday (at 6w3d) and saw one little heartbeat.  And then I exhaled.  I exhaled to see the heartbeat and know that things seem to progressing as they should and I also exhaled to see that it was just one.  I was terrified of multiples.  I am always surprised when people get excited over twins. Babies are a LOT of work.  Toddlers are even MORE work.  Why would I want TWO at the same time in addition to the ball-of-energy toddler I currently have?  I love the idea of three children, but not twins.  I was perfectly happy to see just one tiny perfect little heartbeat.