Hi , Welcome to HCM ,
in young age , most common cause for
palpitation is
anxiety and i feel same cause in your case ,
your ECG and Echo is normal ,
i would like to suggest folowing ,
do not panic ,
stay relax ,
think positive ,
do regular walking ,
eat healthy food ,
say BIG NO to any addiction ,
avoid tea / coffee after evening ,
take your dinner little early ,
do
stress relaxing yogas ,
if problem still persist you can do some test like
thyroid and 24 hour holter study which gives you idea of
heart rate and rhythm for 24 hours ,
congratulation in advance for your marriage ,
take care