How do I tell if I'm depressed or if I have anxiety? ;-;

You can talk to a professional doctor about it.

Explanation: If you think you have either depression or anxiety, I would talk to a professional because both can be serious as I've struggled with anxiety myself. I wouldnt recommend self diagnosing yourself but if you have a hard time being in public without having anxious feelings or cant control your breathing then those are symptoms. If you are sad all the time or have any self harm thoughts then  those are symptoms of depression

Stress and Depression are TWO different things, but relate to each other.

Explanation: Symptoms of Stress ARE Low Energy, Headaches, Intense Heart Beats. Symptoms of Depression ARE Anxiety, Sadness, Low Self Esteem/ Worth, Nightmares, Death Thoughts

As you can see, depression is more serious compared to stress.

answer: i would say the brain but it seem that you have a brain.