So, Lately I've been feeling really sad and I've been cutting myself again. I hate school and I'm starting to hate my life. But those feelings only last for like a week at a time. Could I be depressed or is that normal?

I agree highly with talking to someone trust worthy. Talking about what you are feeling opens the mind to ask yourself why am I thinking/ feeling this way without over analyzing the situation to the point that your are on your bed with the door locked, having the music turned up so no one can hear you cry and talk to yourself (or even a higher power) about your self worth, and with a sharp object in your hand.( not saying that's what you do) That's not a good feeling and I wouldn't wish it on anybody.                         

Try a physical activity or hobbies. Focus all of your energy on it. I say this because I was in a very similar situation and my outlet was talking to my Aunt and while having one of our chats it finally occurred to me that maybe I am doing this to mask some emotional pain with physical pain ,but I didn't know where the  emotional pain was coming from. I also noticed that afterwords underneath the depression and guilt of self mutilation I felt relief and release. It was then that it hit me it wasn't that I wasnt using physical pain to push out my emotions, I was using physical satisfaction to push out my emotions. I was sickened that my physical being was satisfied with self mutilation. So, I set out to find a physical activity that satisfied my needs to push out my emotions until I was ready to deal with them.

 I tried various sports that are along the lines of basketball and soccer, but they didn't fill that need. Sooner or later I found my perfect outlet. My father when he was younger did mixed martial arts. One of the things he did was the nunchaku. He suggested that I give it a try. I did and I loved it. After a month of it I asked myself why I liked it. Again the response I gave myself ,hit me, shocked me. The reason I liked learning to use the nunchaku was I liked the thought of knowing how to physically hurt the people who emotionally hurt me. Shortly after that I was able to find that the root of my problem was poor relationships and my ability to care what others thought of me. Many adults told me that was my problem all along( not saying that what people told you what your problems were right), but it wasn't until I saw the problem with a clear conscience that I could identify it and eventually solve it. Now I am not sharing this to say "hey I know every bit of what you are going through" because I don't. 

Some people can't find people to talk to or are sadly so damaged that they don't trust anyone, especially adults. Some people are to busy to find something to release their emotions/ push out their emotions until they have the ability to deal with them. I can only hope that my story will give you hope that you can solve your problem. The best thing about solving your problems is that no one  can hold it against you that they were a part of your recovery because it was your choice. You have the the power to change your world. You want to know why? Because it's your life. Do what ever makes you happy ,even if it is only temporary. My only request is:

When you wake up write write "I am important( or beautiful, smart, AWESOME. I just want it positive)". It sounds like another thing a psychologist would tell you to do, but make it something you need to hear but don't hear enough. You are the only person who has to be with you. That doesn't mean others wouldn't go through he'll and back for you, it just means be nice to yourself because you have to deal with your self for the rest of your life.

I hope that's good advice. If not, give me a break, I am 14!