sad lately

Lately I've been really depressed. I've gained a little weight, I don't feel the desire to keep up or check up with friends and I don't care if they check up on me, I don't do any of my hobbies any more, I flunked my classes for the second semester, and I've been thinking more and more lately about breaking up with my bf even though he's the sweetest and most influential person in my life right now. I'm really trying to fight this feeling off but some days I don't even want to get out of bed so I sleep until 2pm which is weird for someone who was use to waking up at 6am. Does anyone have any advice?