I Wish I Didn't Get Social Anxiety

I've always had it but only thought about it lately, I suffer from social anxiety. I'm really out going as in I can ask strangers on the street for directions and talk to them like I've known them forever, but when it comes to a university situation, or meeting friends of friends, or being in a large group of people I kinda don't know, I get really quiet and I feel super awkward. I hate that about me. I avoid going to places where I know my friends have their own friends because I know I'm gonna feel awkward and like an outsider since I become really quiet. I'm okay most of the time but sometimes it comes and I just can't get rid of it. It just makes you over think everything and you end up shutting up and feeling awkward.

This summer I'm meant to be meeting friends who come with their own friends, and I've already cancelled going out once and made other plans since I felt awkward, and now I was invited for a weekend at a summer cottage with a bunch of people and I just feel really awkward about it. I replied that I will see if I have other plans just in case I feel really awkward about it and don't wanna go to the summer cottage after all. If I could change stuff about me, I'd change this. I also feel like I don't want to make an effort sometimes in case it gets awkward and rather just sit on my own instead. I think this is mainly because I dread just going to sit next to someone and saying "hi, what was your name again?". Sometimes I'll make friends with perfect strangers just like that, but then there are the times I just want to disappear from the world when faced with a large group of random people. I'm complicated. 

- That photo gives you a brief idea what I'm talking about but my situation definitely isn't that bad! :D