Chest pressure/When to worry?/I am 15

So i have chest pressure not pain,somethimes a little pain on the left i have anxiety and panic attacks so i take zoloft(just started) and helex.My back hurts too.I am unactive and lay in bed all day.I’ve been to a cardiologist a week and a half ago and he said my heart couldn’t be healtier.I am worried it is my heart bc it hurts on the left.Could it be my diet bc i eat unhealty or somerhing serious