Ab's

Hi, Abs are the hardest muscles to get definition and also what everyone wants. You wont get a six-pack unless you've got very little fat around your stomach.
A real good abs exercise to do is "Scissors" where you lay on your back and lift your legs up and down - google it for a better description and video.
If you keep on with the diet and exercise, I guarantee your abs will start to show.

There is no substitute for low body fat percentage when it comes to defined abs. If you don't have to look you are after, keep working. Remember that your weight loss goal is just a number and probably has to be changed as you progress, so don't get caught up in "I have 4 lbs left" and re-evaluate regularly.

However, IMO people tend to train abs all wrong - all reps and no weight. While it is fine to do high reps, your abs are muscles too. If you want them to get bigger (which makes them easier to see) you have to do some heavy weights. Leg lifts and cable machines are what I use and I never go past 20 reps/set (if I do, its time to increase weight).

Just revise your metrics to meet your true goals.