What's your end-game on offspring? You've already passed euchre tournament/golf team/family band.
When we started neither of us were thinking we'd have more than four or maybe five, but as we've experienced the joy of children and as we've more closely walked the path we believe God has designed for us, we haven't yet felt that our family was complete. We still don't feel like we're done now that we have 9 children, so chances are pretty good we'll have another child down the road. Beyond that, though, I don't know.
I hope we stop having kids before we get grandkids, though...
What's the average useful age on keeping your own chickens? Ive always been curious on this, -and then after seeing your setup i noticed some people not that far from me also keep them. Is it worth the trouble?
Chickens will lay pretty reliably up to 3 years, and even then they'll only slow down a little bit. Breeds raised specifically for laying will often lay for 5 or more years. When we had five hens in a small 20 square foot coop we would spend $15 a month on feed and wood shavings, and we'd get 4 eggs a day. So for $15 you get about 10 dozen eggs a month, which is a pretty decent deal given they are essentially equivalent to organic free range eggs that cost a lot more from the store. In the summer you can collect eggs, feed, and water them every other day, so the upkeep isn't excessive.
Winter care is more annoying, though. You get a heated dish for water, close up the cage as best as you can to give them a spot to rest out of the wind, and the egg production drops significantly unless you install a lamp in the coop with a timer so they get 15 hours of light a day. You do have to go out every day to collect the eggs, though, or else they'll freeze and crack.
Given that you already have a dog you have to walk a few times a day, though, it's probably not really any more work than you're already committed to.
What you might find surprising is that the chickens will bond with you and follow you around the yard if you let them out of the cage. They even put themselves to bed at night, roosting in the cage, so we usually let ours roam around during the day - which reduces feed since they eat grass, weeds, and bugs. The eggs probably taste better for it too. Also there is a literal pecking order they develop.
Chickens seem to like having friends, and sometimes chickens die, so I'd recommend no fewer than 3, you can always give away eggs.