Hi Cecile,
Sorry for the late reply.
Firstly, find a new doctor if you can.
Secondly, I am in the US and have had my ileo for 3 1/2 years. I use the Hollister drainable 2-piece system. I used to get 4-5 days between changes when I was inactive. Now that I am back to practicing yoga 2-3 times per week, I generally get 2-3 days between changes. I presume it is the fact that I sweat more now. I also rinse my bag with water when I am at home at night or when I awake in the morning. I feel cleaner when it is rinsed out. I use the plastic bottles from the deodorant that I get. Keep 3-4 bottles by the toilet. You can squirt water into the drainable end and fill it up and release.
Thirdly, does the type of stoma...ileostomy, colostomy, urostomy, have different durations between changes. I would like to hear everyone's stoma type as they answer Cecile's question.