Hello DMC, it sounds to me like you have lost a healthy amount. If you only have 15 pounds to lose then you lost a fifteenth of what you needed to lose. When I first joined I had ten stone to lose (140 pounds) in my first week I lost 5 pounds, which is less than one fifteenth (9.3 pounds would have been a fifteenth). I hope this makes you feel better, what you have achieved is great! Also if you have dieted before you will find that some good habits stay with you, people joining when they have never dieted in their life have huge losses in their first week as its a complete overhaul to their system.
In terms of eating your syns..... Eat them and enjoy them. I have heard a lot in group of people having bigger losses when they have all or most of their syns. Don't forget to have your healthy extras too and plenty of super free and water.
I've lost 7 stone and I find I lose more having red days, in fact I tend to stay the same and have even gained if eating carbs as part of extra easy and green days.
Keep up the good work!