I think it is definitely worthwhile to repeat these tests especially another cardiac ECHO. I assume the CT is of your lung and its circulation.
Before I go further, my first question is about what you were told at the time, and why wasn’t it repeated in 3-6 months? An ECHO is only a snapshot of what is going on at the time and needs to be viewed in context of other clinical information!
Since your shortness of breath has improved, have you noticed any decreased exercise tolerance or swelling in your legs? Most patients with PH initially experience exertional shortness of breath, lethargy, and fatigue, that may progress if the right side of the heart begins to fail.
To reassure you, and before we go further, it is unlikely that your shortness of breath would improve while PH is worsening.
However to help you understand PH better, let me review it here.