I had a lot of problems in the beginning with leakages. Fortunately, I have the most amazing stoma nurse from Coloplast who tried different pouch samples, and persevered until she found the exact solution for my needs. A few months on and my colostomy prolapsed so badly that it needed to be revised to an ileostomy, and we again began with trial and error as I also developed a parastomal hernia and my body shape had changed.
I changed to a Coloplast Sensura Mio Convex light convex ostomy bag with belt taps, that is worn with a belt that holds it firmly in place, no matter how often I bend or turn in bed. Now I no longer have leakages and I have to remind myself to change my bag after several days, 7 or sometimes more days.
I combine it with a halved barrier ring where my skin is uneven, plus a curved elastic tape either side of the base plate to secure the position of the baseplate. The tape is elastic so it follows your body shape and movements.
When you remove your pouch, look at the back where the hole is and you can usually see where the leak is. Mine is at the bottom of my stoma because of my hernia and a skin fold, so I place the halved barrier ring underneath which solves the problem. I halve them as they, like most stoma products, are costly and it's only the lower half of my stoma that requires a bit of help. I use stoma powder around my stoma, and a spray adhesive remover when I remove my pouch. You don't need much at a time.
Please don't feel that you are bothering your stoma nurse as she is there to help you and once she finds the right product for you, life with an ostomy will be so much easier. Don't be afraid to ask for samples.
Best wishes