You already got great answers.
I just wanted to second the caution about swinging weights while you are on the treadmill, especially if you have a history of shoulder issues. It's will NOT significantly increase the cardio workout, but it does put a lot of repetitive stress on your joints. I'd go for steeper, faster if you want more cardio, not toting extra weight. Save the weight for weight training.
If you want more muscle, you need to use increasingly heavier weights. If you can do 10-12 repetitions without muscle fatigue, it's time to up the poundage. 10 pound weights for chest, back and leg or full body exercises are pretty light. If you've been lifting for a year and a half, it's time to graduate!
As Pat suggested, don't just do whatever you can think of every day. That won't increase your fitness level or change your body. Take a look at some of the books or programs in
this thread to get an idea of a lifting program or two.
Have fun!
Mel