Welcome to HCM,
You are having palpitation
and with symptoms that means irregular heart beat, some time it happens at odd times and at other time heart activity is normal.
If your EKG, Echo test are normal ,you still should not give up please get your holter monitoring in which heart beats are recorded for at least 24 hours and depending on result of this study a EPS ( Electro Physiological study) should be planned.
If there is any thing detected and treatable must be treated.
There is no harm in taking second opinion
Please take care