Hi Cathy,
It could very well just be your body adjusting to the switch in programs. I haven't done Atkins, but I have done low-carb, and I found that I gained everything back when I stopped eating that way. That being said, don't worry- WW is a really good, healthy program, and if you're sticking with your points, you WILL lose. You just may not be one of those people that loses a lot really quickly (I'm DEFINITELY not one of those people!!). It sometimes just takes a few weeks to figure out what works best for you to maximize your loss. For me, it's working out, eating the Activity Points I earn, and NOT eating my Flex Points. Just make sure that you're getting enough calories, especially when you start working out. The only other thing I can think of is that those 100 cal packages tend to have a lot of sodium, and that can impact your loss because it makes you retain water. I usually try to stick to "whole" foods wherever possible (Don't get me wrong- I love chips just as much as the next chick!!)
I, like you, did everything right and had a stall in my loss- my leader told me to try eating more, because it was possible that my body was in starvation mode. Maybe you could try calculating the Activity Points you earn from house work and start adding those to your daily points target.... I know it makes no sense to lose more by eating more, but it really worked for me!
You are doing great, even if you haven't seen a loss yet! Adjusting to any program is half the battle, but it will become easier, and I'm certain you will start seeing results.
Good luck!