Q.Orange, Lemon and Kumquat Trees Healthy but Not Flowers
The trees have produced flowers and fruit in the past and were pruned last year. Since then, no flowers or fruit. They are in the ground and about three to seven years old. They have been given three waterings of commercial fertilizer for citrus fruit since late winter.
Certified GKH Gardening Expert
I would recommend adding phosphorus to the soil. This is likely the cause for not flowering, which means no fruit. This article will explain more: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/phosphorus-plant-growth.htm