I’m not happy

Im not sure what to do I’m never happy and always feel lonely im fine when im with my friends but as soon as im not im sad, and im rarely with my friends so it feels as if im always sad. Im a teenager so theres not much i know to do, ive been diagnosed with depression, and take medication for it but am not currently taking it as i forget etc. but it jsut dosent feel as if it dose anything, it dosent make me happy but it dosent make me sad. I dont feel like I’ll harm myself but i just dont know. Dose anyone have advice on what i should do?