Plz help!!! i mowed someones lawn the other day, and i felt pretty calm and got the lawn done, i think i have?

a social anxiety disorder, and so did my therapist. i usually get panic attacks if i got to do something for someone but i was by myself and i felt great, but the thing is if i got to do stuff in front of others, like a crowd of people i usually get nervous and i mean really nervous to a point where my hands are shaking. so i got it done and then the person who i was mowing the lawn for gave me 2 beer, and i drank it and it seemed to bring up a lot of depression and anxiety, but i was still able to have a long conversation with him. but if there is like 5 people standing around, i would just clam up and not talk, and people seemed to notice this a lot, and ask what was wrong, i would never tell them of course, also when someone asks me what im at all the time and then i says nothing, i feel right weird and everything, i would love to work somewhere but this social anxiety is really ruining my life, i have ben like this now for 8 years.. one more thing i remembers helping someone with something and there was, a few more people there, and when i got home. my hands were shaking for a good half hour.. xcan social anxiety really cause all of this