Hello and thank you for using HCM.I carefully read your question and I understand your concern.
You should not worry about.
I will try to explain you something and give you my opinion.
You should know that this heart racing has to do with a rhythm issue. If your heart beats in regular rhythm above 100 beat for minute than we we have to do with a simple
sinus tachycardia.
There are different causes of sinus tachycardia from simple emotional stress,
anxiety, coffee or energy drink consumption, patologyes like
anemia,
hyperthyroidism, or cardiac anomaly.
As you already have done echo,
stress test and this result normal than this is a very good thing.
I will only reccomend to exclude anemia, hyperthyroidism by a simple blood analyze and your thyroid hormones is you haven't done them jet.
Also I would recommend a holter rhythm monitoring to monitor your rhythm tendency to better understand what we are dealling whith and how to treat it.
In my opinion, anxiety might be the couse so you should work with yourself to fight it.
I would recommend to do regular physical activity, because it helps in feeling better.
Hope I was helpfull.
Best regards, Dr.Ervina