Q.Meyers Lemon Tree
Has flowers but won’t produce fruit. What does it need to get the flowers to fruit?
Certified GKH Gardening Expert
If you are seeing blossoms but you get no fruit, this is a pollination problem. You can hand pollinate with a small paintbrush. Just go from flower to flower and swirl the brush inside the blossoms.
Also, have you fertilized? Nitrogen encourages leaves to grow, but not fruit. Too much can actually keep a plant from producing fruit. This article has information on how to fertilize your trees: https://www.gardeningknowhow.com/edible/fruits/citrus/fertilizing-citrus-trees-best-practices-for-citrus-fertilizing.htm
I would also try giving it some phosphorus rich fertilizer like bone meal. If it is lacking phosphorus, it will not be able to produce healthy blossoms (which means no fruit.)