I think that 5 pounds in 3 weeks is great! May I suggest weight training on your off days? That should boost your metabolism and help keep off the weight.
I'm losing slowly too-about a pound a week, which is part of my plan. Whenever I've been too restrictive, I've craved the foods I've banned myself from eating and end up binging. I find that not excluding anything from my diet has helped, as long as I log it and eat a balanced diet, and try to stay within 1800 calories, I'm fine. Some days I eat 1500 calories, some days 2100 but I'm still slowly losing, and I don't feel restricted.
By the way, there's a C25K thread over in the Exercise forums. Come on over if you want to join!