Hey woollbug...both whyspers and notminime have excellent insights, IMHO.
I would only add that 15 pounds in one month is AWESOME.
It's completely normal to stall out after 3 to six weeks of being on Atkins. There's nothing much anyone can do except to stick to the Atkins eating plan to the letter, exercise, drink lots of water, exercise, keep the faith, and drink lots of water. Yeah, I repeated myself. So sue me.
Really, don't worry about a stall. It's normal and temporary, even if it lasts for a few days or even weeks. Things will start moving again. Just read through this site and you'll find that just about everyone has been exactly where you are now. I hope this gives you some encouragement.
One other thing...did you take your measurements when you started your new way of eating? It's often the case that we lose inches even though the scale keeps coming up with the same number week after week.
Keep us posted, and keep up the great work. Really, you're doing fabulously!
Best regards,
Isa