Wild Flower
You are getting some very cogent advice from several people who have been down the road you are considering going down. While we all get over our skies when it comes to relationships, you are at a beginning and as others have suggested there are too many red flags to make the leap.
So little sis, how about you back off(as painful as it may be). Wait on his communication and just keep it friendly like it was before. If he is interested in a different relationship he will be much more explicit than "word". All his responses, in my interpretations, is he is not as interested or is very confused. Neither situation is good for you.
AND IF he actually makes a clearer interest, then you start a long serious, in-depth heart-to-heart chat about your TG-ness. And make him do the talking. You know his gender. He does not know yours and if their is any confusion it will come back to hurt you much worse than anything at this point. And we don't want our cute little sister hurt. While we may be Momma bears, there not much we can do to equalize in your real life.
So sweetie, why don't you work on you, build your real world tg friends, go to school. In other words, be the best girl you can be and let him catch up with you. And if he does not catch up, you have dodged that pain and become a better girl for it.