Sorry you feeel so disheartened
Many of the others on here will have had the same issue at one stage or another too.
is right about the exercise. If you weren't exercising a lot before you started SW, or have upped your exercise a lot in the last few weeks, it will (very annoyingly) slow down your losses. It's due to a build up of fluids in your muscles, and you will most likely see that you start to lose the inches (non-scale victory) rather than the lbs. You will start to lose the lbs as well as the inches, so don't give up just yet
And I agree with Mag104
too, if you are close to what you feel is your target weight, the losses do start to slow down a little.
From what you've said, you're doing everything right. Have you thought about having a few more syns each day? Maybe to 10 a day? Some people have found that if they use between 10-15 syns each day, rather than sticking below 10, they've lost more.
I've always said people should try SW for about 4-6 weeks before they decide to give up completely (and any other diet/healthy eating plan to be honest) Especially when starting to exercise at the same time.
Good luck hun