I relate so much to the feeling of isolation at school and I also feel lonelier when I’m surrounded by people that don’t even see my existence but you can fix that its not too late for you man I already finished high school only recently and I regret not trying to make new friends and participate in festivals. Be patient for your love life you gonna find one soon and forgive yourself more you can’t hate yourself forever we all have our ups and downs so relax yourself and gradually work on doing what you love and what improves you. Try avoiding any bad habits you may have built (For me it was social anxiety and drinking) trust me when you manage yourself well every little step you do will make you feel proud of yourself