I believe we are all here for a specific reason, so that rings true to me. Your Scorpio ascendant makes you seem more reserved and serious than you really are, and some may find that intimidating. Plus you are very emotional and probably to the extent you can't even figure out what's going on with your changing emotions. The Cancer Moon is also very emotional, but again, you are reserved unless with people you know well, so this can be off-putting or confusing to some. Both Cancer and Scorpio are signs which need privacy, so that's why you sometimes feel better at home than when you are out. You need to be in the mood to socialize. The Gemini Sun is your saving grace here, you are intelligent, and this is a more outgoing influence.
It can be hard for others to understand your intense emotions, but Geminis are great communicators. Friends must learn to accept you have periods when you are "on" and ones where you are "off." I am Cancer Sun/Scorpio Ascendant and feel the same way about social obligations. As I write this, I have an appointment tomorrow, and I am considering canceling because I am unsure if I feel sociable enough to go. So I get it (and have planets in Gemini too, so can be very sociable, people think I am a lot more sociable than I really am)!
So it's not your imagination. You are a good listener. You just have distinct public and private sides to your personality. People close to you can learn to live with that. Being a Scorpio Ascendant, you will eventually walk away from those who don't understand you. Why bother with them? Socialize when you feel like it.
You could be a good counselor or life coach since you listen. When you need periods of quiet time, take them and stop being guilty about it. This is just who you are; there isn't anything wrong with you. Embrace yourself for who you are--and you are creative, find outlets for that talent in your quiet times. Take care.