Movicol for impaction advice

Hi, My daughter was prescribed movicol in December as she was passing very large hard stools almost daily.  We were advised to begin on three sachets a day and gradually decrease.  She quickly started passing incredibly soft stool several times a day, (often as many as 8-10 times a day).  After a couple of weeks this regulated to twice a day, thankfully after school, but was still very soft.  On the recommendation of our GP we reduced to two sachets then one now she is on half a sachet a day. Her bowel movements are now solid though still on the soft side but have decreased in frequency. Last week she only went on MOnday and Wednesday.  This week Monday and Sunday. Should I be increasing the dose, I do not want to go back to the runny poo!  Any help please.