I don't mean to be one of those people that act like I am way older than you and I know more because I surely to not and I am only 25. I just wanted to give you a little something to think about. Your sister is involved in puppy love and puppy love doesn't last forever. It may be rough that she isn't hanging out with you especially since you are the same age. I was upset for a while when my sister who is 8 years older than me moved out.
It's sadly a part of getting older. Your going to do a lot of things more apart than together 98% of the time in most cases. And don't worry, love will smack you in the forehead soon too. Just try to be patient with everyone and live your life. It's not worth it to work yourself up so much. I'm in college and my dad thinks I am an ignorant know nothing. I just keep living and let him thrive in his relm of goofyness. Thank goodness we all have a place like this to get out our feelings though, it helps me out I know.