The p wave on ecg was 3.5mm in amplitude and the same height as the r wave. as a dr is this concerning for a patient especially if they are symptomatic?

On the large side: Amplitude wise for a P wave, which can suggest right atrial enlargement, but you "Procedures" section mentions a transthoracic echocardiogram. This is much more accurate for determining atrial size problems than an ECG. Not only that the amplitude criteria is not sensitive and/or specific for right atrial enlargement, meaning it's not a good marker for identifying this problem.