K.B.
I really think the big part of you still losing weight is breast feeding. I lost a lot of weight while breast feeding for two months but then my little one had problems with the breast milk so she has to go on formula. About a week after I stopped breast feeding I stopped losing the weight, I am still trying to lose the finally pounds 14 months later. I really think breast feeding plays a huge part in weight lost after a pregnancy.
You could increase the healthy calories you are eating but just remember that once you stop breast feeding to step back the calorie intake appropriately.
If you are still worried about the weight lost talk to your doctor, express your concerns and ask for advice. They will help ease your worries.
If you are below weight for your height/frame then I would defently talk to your doctor about good foods to eat. Here are a few websites that helps so a healthy weight for height/body frame:
http://www.loseweightslow.com/weightandheightgraph.html
http://www.weightwatchers.com/health/asm/calc_healthyweig...
http://www.healthchecksystems.com/heightweightchart.htm
http://www.halls.md/ideal-weight/body.htm
here is a good one for kids...
http://www.kidshealth.org/teen/food_fitness/dieting/weigh...
Everyone has a little different say about the lows and highs but it should help give you an idea of where you are at.
calorie intake websites, I do not have one that has a space for breast feeding (which would be helpfully):
http://www.ahealthyme.com/topic/cooltools
http://www.freedieting.com/tools/calorie_calculator.htm
http://www.csgnetwork.com/caloriesfemalecalc.html
Hope this help. Best wishes on your healthy adventure.