Robyn, jeans are no longer a "young" trend- they're for everyone. In a dark wash, well-fitting pair, you will look stylish and not at all "old lady trying to look young". I think so many times we prematurely age ourselves out of fear of "trying to look young". Angie has some wonderful posts on age-appropriate clothes and dressing for pear shapes. We still get to have fun with clothes, even if we're over 50!
Maybe you just needed some new jeans. I recently visited my mother who is 76 (although looks much younger) and she rocked her dark jeans in a polished and smart casual way. She also had a great pair of white jeans that renewed my determination to find some for myself.
Hope you can find a great pair!