Lex, it is good to build your skills and career. Getting your job done ahead of schedule will make your bosses happy and as long as its done right ensure you keep that job you like.
However, you won't promote without social skills.
A suggestion: Take at the very least four hours every week on one of your days off and schedule it out of the house. You're earning money, take this as some discretionary time. Go on a walk or a hike, go to a concert in the park, take a class, martial arts is a good one for keeping in shape, arts classes can broaden your horizons, look up something on
http://www.meetup.com/ that interests you and go do it.
Arathain is right. you're being a budding young workaholic and this can hurt you down the road. Make sure you have interests outside your job or you may have tough times emotionally if/when it eventually goes away.
Suineko, no,it usually isn't easy to resurrect old friendships, you've both moved on and developed other interests and aren't the people you once were that made you friends. Making new friends is usually a whole lot less effort. I'm not saying toss the old friends, but just don't expect things to go back to what they were years ago.
What you do is up to you, just be sure it is your dream and not trying to live someone else's.