Is this Angina or not??

I'm a 17 year old diabetic who feels anxious all the time.
For almost everyday, I experienced long-lasting upper chest tightness/fullness/heaviness and some sort of feeling like it was about to burst out.

This pain located at the centre of my chest and sometimes it caused me to breathe from my mouth.  
Last month, I had done all the blood, ECG, X-ray, BP tests but all came out fine except for BP.
The doctors told me I got chest muscle pain due to stress.

Right now, this constant pain does not seem to go away like its gonna stay there forever.

Exercising doesnt seem to start or worsen this pain, but symptoms started from anxiety I guess.

I'm quite convinced that this is either a heart attack or unstable angina, so right now terribly worried about my health.
Can someone help me on this please?

[Leah_]

Try not to worry too much about these pains, as it can only make them worse.
Have you had any pain in your jaw or your left arm?
Angina or signs of a heart-attack usually include pains in the jaw/mouth and arms.
This is because the nerves that tell the brain there's something up with the heart are
near the nerves for the jaw and left arm.
You've had tests, and I think it's to do with your anxiety.
Hope this puts ur mind at ease.