It could be depression, but wouldn't be right for a stranger over the Internet to diagnose you. You say you started taking pristiq a week ago, which is great you are getting treated and sometimes it can take up to 6 weeks to feel a positive effect from an anti depressant. Im also on pristiq, although I started at 50mg, it has been a life changer for me. Iv been on it for 4 months or so now and it's still working great.
Do you have a therapist or school counsellor you can talk with? If not, talk to your doctor about maybe seeing one. It helps to get the negative emotions out sometimes, also coming here for support really helps.
You are not alone in feeling hopeless, i know that feeling all too well. (Hugs)