drop in movement

So im 24 weeks today. For the last 2 weeks ive been having really strong licks, pretty regular. 2 days ago i noticed these kicks got a lot lighter and are only happening every now and again! His heartbeat is fine on my doppler! I called the midwife and she said as long as you still feel something not to worry... has anyone else experieced this? Could he just have moved positions where its not as strong? I cant stop worrying!