You sat in that office and heard the words "this is just a part of aging for some women." Maybe they did a cystoscopy, told you everything looked normal, and wrote you a standing prescription. Maybe they handed you Bactrim until it stopped working, then Macrobid, then Cipro, then another course of Cipro because they were too overworked to check the antibiogram.
The mechanism behind your UTI is not hormonal decline. It is bacterial adhesion. E. coli grips your bladder wall with microscopic hooks and no amount of aging advice will ungrip it. That takes a specific molecule at a specific dose.