You have been given wonderful advice, in my opinion.
I had my first heart attack at age 60 and received my first stents in the RCA. Like you, I started exercising and could walk a mile in military time and lost enough weight that my BMI is normal, and my cholesterol level was almost identical to yours. I quit taking carvedilol and my statin as I thought I had my heart problems knocked, and soon afterwards, even though my cholesterol, diabetes and weight was normal, I had to have six more stents, a pacemaker, and eventually bypass surgery. Today at age 72 I'm back taking the drugs, but I also have Congestive Heart Failure, and believe me, taking carvedilol and Plavix was much easier. I have to sleep in a chair because my lungs fill with water. I made a huge mistake by stopping the drugs.
The dose of carvedilol you are taking is small, but it is a powerful drug. Usually you will be increased to 50 mg a day, that is what I take now. It won't be fun, but carvedilol can remodel your heart. The doctor gave you wonderful advice, in my opinion. Keep us informed.
Post MI we have great data for both beta blockers and statins. For carvedilol post MI with an abnormal left ventricular ejection fraction the benefits are both for mortality and to help the heart remodel to a more normal shape and function. The minimum dose shown to be of true benefit is the 6.25 mg, and I would even suggest increasing your dose instead of decreasing it. For statins, they too decrease mortality and need for a repeat stenting in the post MI period. This seems to hold true in addition to their cholesterol lowering affects.