Being retired, being over 65, not using as much energy (which I assume is not being as active), having trouble getting enough sleep - none of this means you need less sleep.
"According to the National Institution on Aging, it is considered a myth
that older adults require less sleep than younger individuals. Many older adults have a hard time getting the sleep they need, but that doesn’t mean they need less sleep." (National Sleep Foundation) https://www.sleepfoundation.org/aging-and-sleep
Two more things: it's not helpful to measure the sleep you need in a specific number of hours; you need enough to make you feel refreshed, energized and well. That's very individualized, for you it could mean 6 hours, if those hours contain adequate deep sleep.
Also you probably know that it would be better if you didn't have to take the ambien.
I just want to push back against this notion that if you didn't get this specific amount of sleep, you didn't get enough (I never look at the clock from evening until morning and never record # of hours slept, this is a surefire way to get anxious about sleep, which interferes with sleep), and I want to push back strongly on the notion that elders need less sleep than others -
Best ~