Hi Lily!
You are on the right track as far as doing cardio and weight training on a weekly basis.
Now I would suggest to shock your metabolism with another form of cardio. It is quite possible that your body has grown too used to running three times per week and needs to be challenged with something else. I'm not saying that you need to give up running, but instead cut back on it and also add other forms of cardio to your weekly workout. You may even want to add an extra day of cardio(just a suggestion).
You asked about Circuit Max since you don't enjoy step all that much. While I think that Circuit Max will provide an excellent cardio workout I must tell you that 3 out of the 6 cardio cycles involve the step.
We have Cardio Kicks plus one of the Cross Training Express workouts will also be all kickbox(and differ from the Cardio Kicks workout). These are the only two workouts that will not use the step at all. We will also have a Cross Training Express workout that is 10 minutes hi/lo, 10 minutes kickbox, and about 10 minutes of step(but again, there is that 10 minutes of step).
As for arm definition, I noticed a HUGE difference in arm definition just from the punches used in kickboxing. If these punches are done with all out intensity they are a super upper body conditioning workout, not to mention getting your cardio workout at the same time.
If you want to focus more on arm definition with weight training, I would suggest getting Pure Strength Back,Biceps,Abs(complete on one video) and the Pure Strength Chest, Shoulders, Triceps(complete on one video). I would do these two videos one time each per week with a medium weight(rather than a heavier weight). You should see a difference in your arm definition within three to four weeks of doing these workouts.
Obviously, a good healthy diet needs to accompany this fitness routine as well.
Hope this helps!