What does a leaky heart valve feel like? anything?

Depends: If mild, u may not have any symptoms. When heart valves become moderate to severe in their "leakiness" then shortness of breath can occur, dizziness, palpitations=feelings like heart is pumping really hard, too fast or slow, and chest pressure too. But all these symptoms also occur in panic attacks too. Many young females have Mitral Valve Prolapse which people live all their life without issues