It's probably true that extended use of laxatives can have consequences. The better choice, if they work for you, is stool softeners (e.g. Fybogel).
Best I can tell from Shopee, Posh Medica sells several flavors of high-fibre powders.
Note: Have you tried eating ordinary bran flakes for breakfast? Add some fruit.
Note: Whatever you settle on, use no more than is necessary to get the results you need. Too much fibre can actually make things worse.
Note: The classic is a glass every morning of prune juice. It is a laxative but at least it's natural. Del Monte brand is at TOPS.