Personally, I agree with culling her now. She is in excellent shape and the market for cull cows has been good. Udder and attitude not great would make it an easy decision here. Years ago when I was expanding my herd I kept every old cow that produced a calf. Now, if I want to keep any replacements, someone has to go. I am trying to keep the herd size stable. The opens are an easy choice, but after shortening the time I leave the bulls in and culling opens for years, I don't have many opens to cull. Bad dispositions and poor producers go next, but if you cull hard over time there are fewer of those too. Something has to go if you want to keep back any heifers. I think 12-13 is a pretty good place to cull. Mediocre producers maybe 10. A really exceptional cow I am tempted to keep longer, but older cows tend to start losing condition and raising smaller calves. Better to cull when they are still raising a decent calf and in good condition for the best prices.
A few examples: I use to keep most cows until they were open, which meant my herd was gradually getting older with fewer young cows in the herd. I did not have the pastures to keep expanding, so good prospective replacements were sold with the rest of the market cattle. I kept a cow that had been an excellent producer until she was 18. Her last calf weaned at under 400 pounds and she herself was probably 300 pounds lighter than had I culled a few years earlier. She was bred when I sold her after weaning her 17th calf, but if had I sold her and other old cows earlier, I would have had the room to retain some more of her daughters. Another cow was scheduled to be culled for age a few years ago. There wasn't room in the trailer for all, so at the last minute I pulled her out. She was 15, had been a good producer, and was still in really good flesh. I decided one more year. Found her dead of unknown causes the next summer leaving a 4 month old calf to fend for itself.