I have been married for five years and have a wonderful one year old boy. I was always on the fence as to whether or not to have another child. I am a stay at home mom and love devoting all my attention to him. I can't imagine sharing my time or my love with another although I'm sure my heart would melt if the opportunity arose.
I grew up an only child and had no problems other than a very vivid imagination. I love life with my husband and son but don't think I want to add to it. I have a very low tolerance for stress and like things orderly and calm. Whenever I have doubts, I just look at my sister-in-law who has three kids; ages 7, 6 and 3 months, and am thankful for having my one. She never has time for herself, her house is a disaster zone and they are running around everywhere every minute of the day. It also doesn't help that her newborn is colic. She is the type of person who thrives off of chaos. I can't survive in that environment.
Aside from my personal feelings for having another, I was also diagnosed with Kidney Disease and having more children would not be in my best interest healthwise. My Doctor said that pregnancy could progress the desease and I would rather be healthy for my one than not being able to care for two. Even though my health prognosis helped me in my decision, I still think I would have chose to stick with one.
Many families are extremely balanced and happy with multiple children. I think you should decide what is best for you and your husband. Whatever you decide I wish much happiness in the future with your little girl.