nbg, my baby does the same thing, i have days of being able to feel everything so clearly, massive kicks poking out of my tummy and everything, then it'll just go quiet for a day or 2, i was in pieces last time, freaking out but not wanting to panic dp so just imagining the worst. then it all just started up again.
don't forget, a newborn sleeps about 18-20 hours a day, so a baby in the womb probably does too, if those 4 hours of being awake are while your asleep you won't feel a thing
hope all goes well with mw 