Hey Washington, it's been really good to watch this thread (and you!) progress. I don't know that I can add much to what everyone else has already said, but don't worry about the age difference between you and your running friends. Just remember: if they didn't like you, they wouldn't want to hang out with you. Do you relate to what they have to say when you're running with them? You come across in here as being "mature enough".
Also, if you do get asked out somewhere that you can go to (and that age restriction will be history all too soon!), if you'd like to go, just go. Only say no if otherwise the world will end. Above all, relax, be yourself and ENJOY, and don't be afraid to let other people enjoy you!
"Our doubts are traitors and make us lose the good we oft might win by fearing to attempt."