Heart is felt beating when palpated with hand.
But if you feel vibration
over your chest it suggests you have a thrill. Thrill are heart murmurs of more than grade 3 intensity.
Murmurs are pathologic heart sounds
that are produced as a result of turbulent blood flow that is, very sufficient to produce audible noise. Murmurs are the result of various problems, such as narrowing or leaking of valves, or the presence of abnormal passages through which blood flows in or near the heart. Such murmurs, known as pathologic murmurs, should be evaluated by a cardiologist.
Some other symptoms of heart disease
can be breathlesness on exertion or rest, palpitations, easy fatigue, excess swelling of feet etc.
So i suggest you visit a cardiologist for a proper evaluation as many cardiac problems get revealed only in pregnancy
due to the cardiovascular changes of pregnancy.
It can be that at bedtime you are anxious and you feel that you are having these thrills. Also anemia in pregnancy can lead to palpitations. Besides pregnancy itself results in a hyperdynamic circulation with functional murmurs.But its better to rule out more serious causes like heart disease before labelling anxiety
or anemia as a cause.