Social anxiety is crippling my life, what can I do to stop it?

Apologies if this is not the appropriate place to ask this question, I guess I'm hoping that there are other "introverts" on here that have been in similar circumstances and can offer me advice.

I turn 21 in a few months and I currently don't have any close friends and it is really starting to get me down. All through my life I've always been "that quiet person" and I have self-diagnosed myself with some form of moderate social anxiety.

I had a large group of friends during high school and somewhat of a social life but I mostly just tagged along with the group and never became close friends with anyone. Following the end of high school I slowly lost contact with these people. My anxiety kept me from making any effort to stay in touch even though I wanted to. It's silly, but my brain processed it like this "if they don't invite me to things I guess they are not interested in hanging out with me". Ever since then I haven’t had much of a social life outside of my university classes.

I'm not totally awkward, for example I did a great job when I had to do a presentation in front of my class. I was comfortable giving it because I was well prepared and I had already practiced it a few times. So I'm ok with public speaking but conversations scare the crap out of me and I can't seem to fix it.

After I get past the initial fear of starting a conversation I'm ok with small talk but I don't know how to have an interesting conversation. How do I go from meeting someone in class to becoming their friend outside of class? This simply doesn't come naturally to me.

I’m aware that I need to be more proactive and start working hard to build meaningful friendships rather than just letting them dwindle. Any advice on how to go about it?

I don't mean to sound facetious, but it is simple - you must pick up the phone and maintain relationships by talking to people and organising to see them. No magic formula here, just take action.

Thanks, I'll start looking for events and meetups in my area. It's probably a good opportunity for me to get some other interests outside of technology too.

I could say about a few things I notice about myself - I generally don't get past small talk only when I am too much in my head not thinking about the other person. Whenever I start thinking about them, I generally get past that hurdle (given that other person is willing, too). - Also, when I start judging people in my head, or trying to find out if being a friend with the OP would help me in someway, I lose the conversation.

This is what I try to do to fix it: - I try to be humble - without even thinking of bragging about anything (even if I should :)) - take genuine interest (without crossing the line) in OP (e.g. work, education etc) and reduce 'I's from the conversation.

As johnny22 said, join an activity/class you like or have been thinking of taking, develop an interest, and talk to people, respect them, discuss the activity with them; and smalltalk generally leads to 'hi-hello' and gradually to friendship.

All the best.

edit: grammar

Rejection Therapy http://www.rejectiontherapy.com is a game that helps people overcome shyness and social anxiety by taking on small challenges. Each challenge increases your comfort zone and your confidence.

I've done the 30 day Rejection Therapy challenge and, while it wasn't easy by a long shot, it did help me immensely. I'm much more comfortable starting small talk with strangers than I was before.

Remember, your comfort zone is elastic. If you don't stretch it, it will retract.