Congrats on the baby!
I'm small too, and always have been. I didn't have any trouble losing the baby weight. I weighed 111 lbs before having my son, gained 40 during the pregnancy (he was 7lbs 9oz) and 3 days after having him I was down to 115.
I've always been really active though and worked out with weights, ran 8.5 miles a night, and played tennis a lot. It's probably what helped me through a 37 hour natural child birth, first and only child, and I was 35 years old doing it.
If you cut your calorie intake by just 100 calories a day, and increase your daily activities just a little, it helps a lot. In order to lose 1 lb. you have to burn up 2500 calories. One pound = 2500 calories.
Don't go crazy trying to get rid of the weight too fast because you'll only make yourself sick. You have to lose weight slowly and in a healthy manner in order for your body to stay healthy, and to keep it from coming back on.
Get yourself a set of ankle weights that weigh 2 lbs. each. The kind with the velcro strap are the best ones. Strap those puppies on in the morning when you get up and then do your housework with them on. This will bring back muscle tone and help to burn up a few extra calories without having to resort to a major calorie cut in your diet, or overdoing it with exercise. After just having a baby it's best to avoid anything too strenuous.
Also, if you eat salads, try eating it with vinegar and oil dressing. Vinegar helps to naturally lose weight.
hope this helps ...