Hello!
First of all, congratulations on your weight loss so far.
If I read your post correctly, you lost 13 pounds in a month - that's a lot of weight. Perhaps your body is just "catching up" now. That's what happened to me early on. I was eating on plan and exercising several days a week but the scale didn't move. It was frustrating after the rapid loss I'd been experiencing, but after a week or so I slowly but surely started losing again.
Are you keeping track of your measurements? I'm not as good about that as I could be, but I've heard/read others say that they notice changes in their body when they eat well and exercise even during the times when the scale won't budge.
Good luck!