WHAT am I doing wrong???

I'm typing in red today because frankly, I'm starting to get mad. I do not understand what I am doing wrong, I really don't.
I'm following the Weight Watchers Flex program. I am getting pretty good at eating most of my points everyday, though I do not always hit it. They encourage the "good health guidelines" so we don't use our points for junk. I am hitting those every day. I have cut out the majority of processed foods. I am exercising. And I feel like I'm barely losing weight. This week I lost the .8 that I put on last week during that 'time of the month'. So in two weeks I've lost nothing. In 12 weeks I've lost 18. I guess I should be totally happy with that, but I'm not. It seems like everybody else in my starting weight range is dropping the weight like lead filled ballons. What am I doing or not doing?
I keep telling myself that if I'm eating healthy and exercising, that should be all I concern myself with, because the only other option I can think of is not eating healthy and not exercising. Well it doesn't take a rocket scientist to figure out that is the answer, either.
So I don't know what is.
Please.
Send.
Help.