If left alone, when will kittens stop nursing?

Hello! I have three kittens who are 17 weeks old today. They all started eating solid food of some sort at around 8 weeks old. Their mom and they were all spayed on June 15th. My question is when will they stop nursing completely if I leave them alone? I'm was an abandoned kitty that we took in from our neighbors, who ended up with the cat after a friend of theirs dumped her on their doorstep. They did not want her. She had one litter with them and she was pregnant again when we took over her care. I know she is afraid of being abandoned again, but we do our best to make sure she knows she has a permanent home now. I believe that she still nurses them partly out of comfort, but also, frankly, the kittens are all big enough to take her down and nurse whether she likes it or not. Separating everyone means throwing her outside again, which I do not want to do to her right now. She may misunderstand. Will she eventually dry up and stop nursing on her own at some point? I will not be getting rid of the three girl kittens, and I really do not care if they nurse for a while longer, but feeding them is problematic as long as they nurse too. I also do not want them to go back to nursing exclusively. It would seem they do not bite her enough for her to prevent them nursing either. Help?!

They will not nurse exclusively at 17 weeks.  It probably is a comfort thing.  When mom has had enough she will let them know.  Are you feeding the kittens enough food?  They eat a lot and need at least twice as much food as an adult cat.

They get to free-feed three types of dry food. In addition, one kitten will eat nothing but wet, one will eat nothing but dry, and one eats both. The trick has been finding what flavor/ brand of wet food each will eat (it changes every three hours). The dry has been easier to figure out, but that may be changing (wanting adult kibble instead of kitten kibble now). I have not slept much in my own bed since December with these cats. That is when mom and her older son first began coming in at night because of the cold winter weather. Then, once the kittens were born, I was on full-time recliner napping duty (still am) trying to make sure they had what they needed, were using the litter box, are not tearing up my house too much, etc. Because of the nursing, getting them to eat enough cat food has been troublesome, but their weights seem ok. Between 4-5 lbs for each. They actually nursed far less before they were all spayed! Sheesh!

At 17 weeks they still need the kitten food.  It has extra vitamins and fat that they need.  Mom could eat that too if she is still nursing.  Have you tried offering the kittens KMR?

Your kittens are suckling mom for comfort not nutrition. She should dry up very soon. She will stop this activity when she is fed up.

I have kittens the exact same age and they still try to "nurse" but mama is getting up and walking away more often now. Kittens will nurse as long as mom lets them, but it's usually over by six months at the latest.

Your kittens sound well-fed and healthy. I wouldn't put anyone back outside. They are just being cats.

Hopefully you can get back into your own bed soon!