When a person quits drinking, normally their list of friends will undergo quite a bit of revision. Successful recovery pretty much requires you to avoid your drinking buddies and often these are the only buddies you have. So, there is a social transition involved in sobriety; an abrupt loss of old (and often good) drinking buddies and a lonely spell while you make new, sober, friends. There are many things that can help: new hobbies are great; getting involved with a church can lead to new friendships as can involvement in political action groups; just going to the library and reading can be interesting and instructive; take a class or two at your local community college; sign up for an online course and work hard to ace it; the possibilities are numerous. As is often noted on this forum, quitting drinking it the easy part, changing the person who drank is much harder. It can be a lonely struggle at times but it is worth the effort. Best wishes.
Added in editing. There are several non-12-step programs that can help provide structure for your sobriety. Two that come to mind are AVRT and Lifering. If the idea of AA makes you uncomfortable, these are frequently recommended alternatives.