I keep feeling sad and angry for no reason

I often get very angry or sad for no reason!

I am a seventeen year old and today at school I just started lashing out and kicking the plants... I even kicked a wall

And then I just lie on the school field for about half an hour staring at the sky, my heart rate high and my body twitching in anger. It all felt very weird.

And when I was on the bus on the way home I felt so sad and drained. My eyes were empty and lifeless. I had no expression on my face. I often feel emotionless

I often do feel very empty and drained. I often make up for this by drinking and acting impulsively...

I also have no idea who I am. I just am very confused and angry and sad.

17 is a difficult age to go through for many...it was definitely one of the most challenging years of my life. Hormones and all that fun stuff definitely play a part, but you might consider getting your blood tested just to make sure everything is healthy physically. Sometimes mental health issues have a physical cause.

If you are physically healthy, then it may be time to speak to a therapist or psychiatrist about what is going on. Perhaps they can provide support and meds if required.

I agree with scaredandconfused: rule out any physical causes and if that checks out then you might need to see a psychiatrist to rule in or out mental issues. I hope you find some relief soon.

I agree with ScaredandConfused 100%
get to a Doctor. Make sure you document all that your feeling & those symptoms.
You are at a very difficult age. I went through the same thing at 17.

17 is hard. My time at 17 was hellish, and it was the same with my daughter.

I think what's been said is good advice.