Am I Doing This Right?

I started MFP abour 4 weeks ago and have lost 8 pounds so far. I allow myself (well MFP allows me) 1,590 calories per day and I frequently burn around 500 per day with exercise. A typical day is:
wake up-have coffee and a protein shake
go for a 2 1/2 mile walk (burning around 200 calories)
have a protein packed lunch (chicken on salad, hummus, etc.)
have a snack (hard boiled egg....peanut butter on an apple)
go for a 2 mile run before dinner (burning around 330 calories)
eat a healthy dinner.
(every other day I do calisthenics/strength training)

Is 8 pounds in 4 weeks typical? I'm happy with the progress so far but I see people with these insane numbers and wonder what I might change to see more results. I tend to eat back some, but not all of my calories, because I figure MFP already has you at a calorie deficit...so I don't want to go into starvation mode.
Any suggestions or changes would be great to hear about!