Pregnant and feeling very depressed

Idk what's wrong with me. I'm 12 weeks and every since probably 7/8 weeks I've been SO depressed. I don't want to get out of bed. I haven't been exercising. I've been slacking in my classes (I'm a college student). It's hard to get myself to do even the smallest tasks. Also I've been having a hard time accepting my little bump? I love this baby and I'm so excited, but I went from being so tiny to not fitting into any of my clothes. And everything is uncomfortable. Has anyone else ever gone through this? Also, I don't feel pregnant. It's like half of the time I forget im so nauseas/sick constantly for the baby and I forget there's a good reason for it.