Willow
I'd go 7-10 days between movements around the 14-18 week mark with Hester. (I know you are supposed to feel things earlier with subsequent pregs but try not to worry.)

Do you know if you have anterior placenta? Did they tell you at the scan?

If it's doing your head in - which would be understandable after your loss - get a midwife or ob to do a doppler for you to set your mind at rest.