My first question to you is are you still breastfeeding? If you are, and you've lost the amount of weight that you have said, then it makes perfect sense that you are so hungry and wanting to eat. If your concern is high, then it is never a bad idea to get a professional opinion.
Take everything doctors say with a grain of salt though, especially if you don't know the dr well, or if the dr doesn't necessarily respect your health lifestyle, such as eating organics or something. I've had drs like that. As far as weight loss, keep up the exercising-great job 40 lbs!
Make sure you have both an aerobic workout (like running, treadmill, intense pilates to riase heart rate), and an anerobic workout (like weights to build muscle) in place. I love pilates, yoga, and exercise with weights done on the ball. Also keep in mind that muscle weighs more than fat, so if you notice hey, I'm looking pretty good, but I now weigh more, its most likely muscle gain, and thats great.
Oh I'm sure you already know this, but limit or cut your refined sugars, and grains. Drink plenty of water. Cut out soda, sweet tea, and pesky things like yummy creamers in coffee. Those are low in fat, but there's a ton of sugar in them. Also something you may not know is eating organics can help. Our bodies hold in all of those toxins, pesticides, and hormones. Then the toxins hold in the excess fat.