I'm Capricorn with Aries rising. I share the impulsivity but not the self-confidence of that sign. Why so?

I do believe I'm a pretty strong character and I'm filled of creative energy and have a lot of confidence in my ideas, my values and my qualities, tending to express myself intensely once I've gained confidence. I think I'm fairly competitive, arrogant at times and very very impulsive. Yet I don't think I'm a too aggressive character (yes somewhat dramatic), and I do have a lot of insecurities, fears and contradictions. Unlike most Arians, I'm somewhat more abstract and very aware of myself and as well very hard and self-critical. I am not too active and ertive either, and tend to be somewhat unfocused, something not shared by Arians. Would that be something maybe brought by the fact that my sun is in Capricorn.....what other signs and planet combinations you believe might be decisive in this lack of energy and of confidence that most Arians do not have?