If you're already doing a day of abs, plus abs at the end of every workout, I can you right now you need to back off. Abs are like any other muscle and need time to recover. If you're doing abs every time you workout, you're probably doing too much.
I would also recommend doing additional exercises for each muscle group. Only 3 sets on a bench press machine isn't going to be terribly effective if you're trying to build muscle. Weight machines are okay for beginners, but free weights are going to be more effective in the long run. You should also throw in different exercises. If you're trying to stay relatively low-impact, pushups are a fantastic chest workout. You can do other things, like flat bench, incline bench, cable crossovers, dumbbell flies. If I were you, I would try and do at least 3 different exercises at 3-4 sets a piece for each body part.
To burn more calories, you can superset these workouts to keep your heart rate up and avoid too much rest time. Do a set of chest followed immediately by a set of arms and alternate back and forth until you finish 3-4 sets of each. Then rest a minute before moving on to the next set of exercises.
Above all, you need to keep your diet in mind. Your diet can make or break any workout routine.