I've done everything...still no eggs!

So I have done everything that I know and have read to do and I still don't have any eggs from my 4 chickens, so I am hoping maybe someone can offer suggestions or at this point even words of encouragement. Three of the chickens are now about 31weeks old (1 RIR, 1 Golden Comet, and 1 Buff Orpington) and then 1 is about 24 weeks old (Silver laced Wyandotte). I thought for sure at the very least the RIR and the Golden would be laying by now. They have three nesting boxes that I put straw in which are 15''x15''x15''. The coop is 3'x5' with two roosts although they all really huddle together on one. The run is 5'x10' so it is really big. I use pine shavings bedding in both the coop and the run and this hasn't seemed to bother them. The run also has roosts for the girls to hang out on. I used a grower finisher crumble up until about two weeks ago when I gradually started to mix in a layer crumbles. The transition hasn't phased them, they are still eating and seem happy. I give them fresh water twice a day and add in a vitamin supplement that provides extra vitamins A and D and calcium. I live in Ohio and we are entering Fall so now I am facing less daylight and colder temps. This week I am going to put lighting in the coop and have it on a timer to come on giving the girls about 14 hours of daylight. If anyone can offer any other ideas, tips, or suggestions I am open to anything at this point.

It is probably because of less daylight. I have some young chickens (under a year) that have not started laying as well and I am going to set a timer to turn lights on and hopefully that will do the trick. I hate that I am getting two eggs a week.