Hey, One I can help on!
It is perfectly normal to see your heartbeat in your sternum or abdoman. All it is, is your aorta pumping oxigen rich blood to your trunk! The only serious think it could be is an Aortic Anerysum, and they would have caught that on the echo. It generally does not incur in young people, and comes from years of high blood pressure.
Don't worry about seeing your heartbeat, bro. It's a lot better that not seeing it!