Depression? Stressed about that too.

I am a 25 year old girl . I started experiencing these symptoms last august September. i lost interest in anything. all my emotions were turned off. i used to cry for no reason. i preferred staying alone. once I had a breakdown i n October. i spoke with my family and it did better. but i have changed since. now again i get irritated easily. I have now anger issues additionally. I know that somethings i am doing wrong but i am not able to not do it. i tell something to people and then feel upset about telling that to them. and few few hours i get back to normal. my sleep and appetite are pretty much normal. except about the fact that i tend to overeat when i get upset and have sudden cravings. i don't normally share anything much with my family or friends. i have started maintaining a journal now as i have heard it helps. I have trouble concentrating also. i have a lot to study this year. am additionally stressed about that too.