OK, I have a few thoughts.

Although I'm not a believer that meds are the answer, in some cases, they can be helpful. I have a prescription for Klonopin that I only use for situations that really maximize my social anxiety. For example, if I have to do a presentation to a small or large group, if I have to be in a meeting with supervisors, if I have to do an interview, etc. I would speak to your doctor or psychiatrist about this. It helps.

Another thought, if you are conscious of your leg shaking, lack of eye contact, etc., can you not control them to some extent? Plant your feet flat on the floor, deliberately make eye contact although its uncomfortable? I am aware that I avoid eye contact, so I make a conscious effort to do it, even though it feels scary. Also, do you know for a fact that is why you didn't get the job? You may just be assuming that.

Another thought, you can take some online classes to get some skills. Many employers need people with specialized skills... like computer programmers (who also don't interact much with people).

Another thought, start with baby steps. If you don't like leaving the house, set a small goal such as going to Walmart and saying hi to the greeter. Or walking down the driveway or street. Then set another small goal. You don't need to leave your comfort zone in leaps and bounds. Do something manageable but still somewhat uneasy. Take baby steps till you get more comfortable.

Also, I go through terrible blushing episodes when I first start a job, usually with authority figures but often with others. They will last for about 3 months. I feel embarrassed like you, and it is difficult to face people and go through this day after day. However, I have come to realize several things. People are way more understanding then we give them credit for. I have comfortable and even friendly relationships now with coworkers who I blushed and choked with initially. If they thought I was a weirdo when it happened, they didn't keep that mindset forever. Also, having started several new jobs in my life, I have realized the blushing episodes EVENTUALLY do go away. Not as fast as I would like, but they do. If you talk to someone 200 times, you eventually get comfortable, as you probably are with your boyfriend. Don't get me wrong, I hate the anxiety and blushing, but it does reduce in time. IF you keep going despite your feelings of self hatred.

By the way, I am what most people would consider successful... I am a director and make good money. My point being - it IS possible to work with this condition and even do well. But start with baby steps