If you had a strong family history with many males in your family dying early of cardiovascular disease, or if you were grossly overweight and inactive, and *IF* your doctor had medical reasons to suspect you were ill, yeah, perhaps you could think of the possibility of cardiovascular disease.
But (a) you don't mention anything like this, and (b) you really are statistically too young, and (c) you have a doctor who has actually examined and treated you, and he--being medically trained--believes you are suffering from white coat syndrome, and has not suggested any other medical problem.
You have either been told or have deduced that you are suffering from health anxiety, which is what makes you miserable and which is pushing your blood pressure up.
I think you'd be both happier and healthier if your doc gave you a referral to a professional who specializes in the treatment of anxiety.