Dear friend, welcome to HCM!
It is common to have pulsations felt above the navel in thin lean individuals.
Since USG was normal, there no worry about the aneurysm
If you are thin and/ or anxious, you may feel pulse of the abdominal aorta
easily. Neglect and be happy.
Take care and please keep me informed of your progress.
I hope to have answered your query satisfactorily.