Feeling slight pressure and burning in chest near to the left upper side. I'm only 17 could this be heart related? Doesn't feel like heartburn

Not likely. Not likely to be heart related, at your age. Pain and soreness in the middle of the chest, either on the left or right side of the breastbone, also with some soreness if you push on the area, may be from costochondritis, a common condition in growing adolescent who are otherwise healthy. Make an appointment with your doctor to check it anyway to confirm this and rule out other causes of your pain.