Goodness, it sounds like you have been through such a lot 
I couldn't say for sure if what you experienced when you were younger is what is causing your social anxiety now, but I would be amazed if what you went through hadn't left you with anxiety (social or some other kind). I think anxiety itself is such a complex thing, and there are a lot of different types of anxiety and they can overlap each other. My social anxiety for example was just one part of my general anxiety over all (fear of adult life / fear of driving etc), and it can be really really limiting to your life. At 30 you are still really young, only just out of your twenties, and I think between the ages of 18 - 32 is when we change the most as people - it can be confusing and quite eye opening. I don't think anybody can say they are the same person in their mid thirties as they were in their early twenties.
I didn't go and see anybody about my anxiety, at the time I didn't think anybody would be able to help me and I blamed myself for being weak and pathetic - it never occurred to me to seek help. I got over my anxieties naturally with time. It wasn't a quick or easy process but I am pretty confident that the reason I have got past a lot of it is because I have been in so many situations during the years which have sent my anxiety through the roof but which I had no option but to face and deal with - and I got through each horrid thing that I had been dreading and nothing terrible came of it. Sometimes with fears the only way to get over them is to face them. When my DD was born it never occurred to me how many social situations that would force me to be a part of, how many people I would meet because of her, and although at first I found it really difficult it just got better the more I was thrown into it. Another example (not social anxiety but a BIG anxiety none the less) was driving. I was literally petrified, in fact it was a proper phobia for me. I passed my test at 17 and then didn't drive again for 12 years! I avoided putting myself in the situation I knew would make me feel so awful and which I knew I would hate - then my DD came along and I realised how limited her life would be if I didn't drive and so I just had to do it. I hated hated hated it - I was so scared I would feel sick, sweaty etc but I got over it with time. I would never ever have done it for myself though, I would have avoided it forever. Now I am fine with it.
I would hope with time and life experience your anxiety will lessen. But the one thing I would say is that even if you dread doing something don't avoid it, because you are feeding your anxiety. It's like a monster sitting on your shoulder - every time you avoid a situation because you fear what may happen or what somebody may think you are feeding that monster. And what you need to start believing is that nobody else out there is perfect - nobody - and that ultimately so long as you go through life being a nice and good person it really doesn't matter what other people think, they aren't any better than you.
I think that it would be a positive step if you sought support in the form of some kind of therapy. I think it is VERY important that you find the right kind of therapy and the right therapist for you - I think they are like shoes, you need to find a good fit and the right person to help you. If you find that the first one isn't helping don't give up, try another one with a different approach. It sounds as though your anxiety is making you very unhappy, and I think seeking help would be a really positive thing.