I am also 14, and I know some people who have been depressed. I think you definitely could be depressed. Depression doesn't necessarily mean that you are so sad you are incapable of doing or saying anything. Thoughts and consideration of suicide is a factor and random down mood swings of course. Just try your best to remember that you are worth it to people in this world and you mean a lot to the people close to you. Whether they be family/friends or classmates. You'll get through this, you just need the motivation and the effort to make it happen.
Hey there. I have suffered from depression for many years and also suicidal thoughts at times. It definitely sounds as though u may have mild depression. But if u r having suicidal thoughts of any sort then you need to seriously think about talking to a therapist. This is a great first step. Find people who are going through same stuff. Remember that even if you are depressed it does not mean you always will suffer from it. Life is hard and crazy hard at your age. Sometimes we need some help to get us over the humps. Please don't feel like you can't talk to someone in your life about this. Family friend support is key. Life is worth it I promise you.
Yes, it could be depression. You should definitely talk to a therapist and get proper treatment. Try to get into sports and other activities that make you busy and happy.