First you nest box is rather large for the cage . all you need is a box 24inch high 14 inches square.

To encourage breeding your birds need a good quality seed and green veg diet,never feed breeding birds pellets.

The best green food is Broccoli, Kale, Sprouting seed. Dandelion Leaves and seeding heads, Wild grass seeding heads.

The rest of your cage items are fine

DO NOT as some one has stated cover them , they need plenty of light , this encourages them to breed and carry out mating .

Having been a breeder of Cockatiels and other Parrot like species. I have found as near natural foods are the best .

Soaked seed is easy to prepare soak some of their seed overnight in warm water , drain rinse , place somewhere warm till it sprouts , rinse and feed to your birds from Now till any chicks are feeding them selves.

Remember only 1pair per cage for successful breeding any more and the will fight .

To ossama if your bird has what appears to be bars on it's tail it is a female.also check under the wings ,if there are what appears to be yellow spots on the flights ,it is a female . a Male will not have these also if it has not yet molted these are on both male and female I can not make out if yours has.

Avian Care Consultant and ex breeder

you need to make sure they are in a dark place, so put a blanket over the cage, they can breathe under it just fine. also try not to be in the same room and make sure its quiet so they have privacy. if you leave them like that for about 2 hours they might have bred but not for sure.

That bird you posted a picture of is a male.

SO IS THIS MALE OR FEMALE