What am I doing wrong?

I got to OTF about 3 to 4 times a week. I have been a member since July. Probably in Oct is when I upped my classes. My weight fluctuates only a couple of pounds. My arms are getting toned but I cannot notice any other changes. I try to track my food intake. I do fairly well during the day but in the evening I tank. I don't know what I should eat or stay away from or eat in moderation. I love CARBS. Any suggestions?