I don't check this web site often ---just read your question from Jan 2012 asking if there are other young atheists in the Pgh area. Go to meetup.com. Enter "Pittsburgh" and key words such as "atheist" "freethought" "skeptic" etc. and you will find several groups that meet regularly in the area. You can also enter other key words for your other interests to find groups that may interest you.
Once you join a group, you can leave comments on the discussion area stating you are new to the group and a recent high school graduate and are interested in meeting like-minded young adults. Also I believe there are atheist or freethought groups at Pitt and CMU ---perhaps other local colleges. If you call the schools, they will probably be willing to pass your info to someone in charge and you might be able to attend group meetings, even if not a student there. If you are attending college, you should be able to find a group at your school unless, like Duquesne U., the school will not allow such a group to meet.
Hello Danielle, and welcome to this wonderful world of rationality, truth and peace. True common sense helped by science leads to atheist wisdom as freethinkers like you know well.
We invite you to make good friends by joining the busy group "ORIGINS: Universe, Astronomy, Life, Earth, Humans, Religion, Gods, Atheism, Evolution, Darwin..." with 600 discussion topics and 3200 members.