welcome to beyond blue.
my son just finished high school and was going to Uni (this year) until he worked out that it was not for him. He does not associate with many of the people from high school but that would mainly be because his interests and their interests were/are different. Between say grade 1 and grade 12, his circles of friends changed based on interests or changing schools etc. After grade 12 you might go to Uni and develop new friendships - this may take you away from your home town as well.
You said that you don't message your old friends because you feel you would be burden... Last year, I contacted an old friend that I had not spoken to for MANY years. He said he was concerned for me and we decided to catch up for coffee later. We did and chatted about many things including my issues. He wanted to learn about mental health etc. Sometimes what we think that others might think about us is the opposite. You only have to start with "hello, how are things going with you".
Relapses are possible. Ca you remember what distraction or coping tools you were given when you saw them? What is stopping you from talking your GP or going back to your psychologist again?
Lastly, when things were bad for me, my mum was the first person I spoke to. I am not going to saying it is their job to worry about their children, but they would care to know what is happening to you? My parents and I have a line that I don't cross; that is, I know how much to tell them without going into too much detail.
You story was not boring - in fact, other users might identify with it. In fact that is somewhat how I started here. I found other stories that were mine. So I want to to know that you are not alone, and the people here are friendly and supportive.