No lemons on my 5 year old trees zone 9b

I have not had any Leomons on my 5 year old trees
Citrus trees , zone 9 b
I tried compost and citrus fertilizer
Nothing works.

Were the lemons grown from seed or were they grafts? I've heard that seed grown lemons can take up to 10 years before they produce in some rare cases.

I hope the trees are producing for you soon, that many years is a long while to wait!