It takes a lot to over-train, esp. if you are a beginner and not lifting heavy weights, etc, etc. I think that at this point that if you enjoy doing that much cardio, you can continue to do it without negatively impacting the strength training. As you progress with the lifting and possibly start to focus on getting real strong, however, you should definitely re-think your routine and start to do cardio & lifting on different days. But right now, if you are losing weight and feeling good, i don't think you need to change things drastically.