Personality disorders..?

i know everyone has their ups and downs and days where theyre loners, but lately it seems like ive been having alot of downs and very little ups. i actually enjoy being left alone rather then dealing with people. i find it difficult to remember the last time i was truly happy. bipolar depression runs in my family, so it is a possibility i have that. im not homicidal or suicidal, but i do have times when i find myself feeling worthless and hopeless and like life is pointless. im not sure if there is really something wrong with me or if i just want to be diagnosed with something so i know exactly whats wrong with me. since ive been doing research about what possible disorders i could have, there are 3 i think i may have: cyclothymia, bipolar depression, or schizoid personality disorders. my mom is going to make me an appointment at the behavioral health center, but id just like your opinions, what does it sound like i have to you? thanks in advance - Lana.