You've gotten a lot of incorrect advice here, at least I disagree with it. I don't know if you are still in a relationship with Alex, if you are twelfth house composite shows the couple has a need to retreat. To transcend ego. The couple must do this or it will experience grievance losses.
The composite is not about how you relate to each other, rather, it is about the experiences you as a couple will have/need to have.
As for your own natal 10 house Sun and Mercury well, that doesn't mean you are an extrovert. Tenth house is the myth the public sees, the people who don't know you. And here you are writing on a forum! - Sun (you) and Mercury (communication). See?
Ahahah , I never was good at Astrology (though I might guess a Sun Sign or Ascendant at first sight on occasions =), and I am not a good student because I don't spend time to apply and improve, but it's very educating to read all the questions and answers on this forum. It was some kind of relief finding out that really some things may happen for a reason that is outside of my control, because it's just the way it is or has to be, since the planets do have an influence on us. If I was left alone I'd make an even bigger mess!! Lol
The shape of your face does remind me of 2 (girl-)friends of mine- both are Aries, and one has a Cancer Moon, the other I just remember has one of her big 3 in Capricorn... So... Yeah, I got the clashing part of all your squares. By the way, all you 3 girls have pretty faces.