Hello, welcome to social slimmers!
I'm another SW follower, and I agree with everything kaybird says, although I will add that you should try your best to have at least 5 syns a day if you can.
Using your syns does help you lose weight. Cutting them out completely, or barely using any at all, can give you a fantastic loss one week, but you will then see that your losses will tail off and possibly stop altogether. We've just recently had a member in group who was advised to increase her syns to 5 each day as her losses had virtually stopped and she was really annoyed. It turned out that she was just using syns on a single bottle of Prosecco at the weekend, so she wasn't having enough across the whole week. Once she started incorporating more syns, she lost 4lb the following week!
I know I sound like an advert for SW, but I've been there long enough to have seen so many people come in without using more than 20 syns in a week and be really annoyed with not losing anything. Make sure you use at least 5 each day, you don't have to use all 15 each day, just use some
Best of luck for WI next week, and you can get to your happier place if you stick to plan!