I need understanding

 I'm 17 and I'm trying to figure out what's wrong with me. I don't understand how I'm feeling.  I'm not sure but I feel like I might have depression. But whenever I bring it up to someone I'm told that I don't. I'm a person who's happy when I'm around others but when I get by myself for to long the tears come out. I get sad about anything one minute I'll be fine but then I'll get into my head and start crying. I'm an insecure person I feel like no one really likes me and I annoy people with my presence. Lately my goals have been shoved aside I realized that I'm not as motivated as I once was. I skip class more often and I don't do my homework sometimes cause I just feel tired or just uninterested. I've managed to keep up My grades to a B but will power is starting  to fade. I sometimes regret taking classes so early cause I don't want to get up to go to school. I wanna just lay in bed.
Is this some kind of phase?? Is this something else?? Is this just me being hormonal or something??