reaching out?

im 17 years old and the past year and a half have been hard. i don't really know what the hell is going on, i go through these phases that i slip in and out of where im okay then all of the sudden, i get hit hard with complete like emptiness. i just feel so alone and I tend to isolate myself already but it just gets suffocating and im really struggling to stay afloat if I'm going to keep falling into this. i also have a few bad habits and probably unhealthy coping strategies but none of my friends have ever been through this nor do they care, and I'm very distant from them anyways. i just dont know what exactly to do I just know I can't live like this and it feels never ending. i have started to think things I don't want to so if any one has any idea how to move forward or move on from whatever this is, it would be appreciated. i tried to talk to an adult I really trusted but I got the impression they thought I was pathetic and I felt dramatic and that's the last impression I want