Have you been drinking enough water? If you haven't you could be storing water due to all the pasta and noodles etc you are eating. IF you have sts the tomorrow- DON'T PANIC!. Stick with it. Some people don't loose the first week- and then go on to have good losses.
As for syns- don't forget you don't have to use them on snacks etc. You could use some on salad cream or mayo with your salad at lunch. Or you can use oil in cooking and syn that (1/2 a tbsp of olive oil is 3 syns and is plenty plenty for roasting your veg up nicely
) Buy some mini bars of choc and make a point of treating yourself on an evening with an Options hot choc (2 syns) and a Cadburys Fudge (5.5 syns) for example.
I would say though- the main thing is making sure your drinking enough water when you are doing green days. I store water like a camel if I don't
lol