Please help me I want her to be a bit larger so she can lay eggs
It is most likely genetics, sex-linked dwarfism is a recessive gene (dw). The father could carry one gene and still be a normal sized chicken. The mother would be normal because she does not carry the gene, The offspring that are males will be normal sized because they will only carry one of the dwarf genes but some of the female offspring will inherit a dwarf gene from the father and be dwarfs or smaller in size than normal chickens.
Females can only carry one sex-linked gene for a trait- males can carry two. Males inherit one sex chromosome from the mother and one sex chromosome from the father. Females only inherit one sex chromosome and that comes from the father.
There is a recessive autosomal dwarfism in chickens (not sex-linked). Both parents would have to carry one recessive adw ( autosomal dwarfism) allele and a normal allele. When the parents are crossed, some of the offspring will be noticeably smaller than the parents at maturity.
If it is not genetic, then it would have to be a medical case where something is affecting the growth factors in your chicken.
There are also other kinds of recessive sex-linked dwarfism, and these may be involved but they are all recessive like adw. Two others are bantam and McDonald, both are alleles to dw. There is also a dominant sex-linked dwarf gene but it is not involved in your situation.
Dwarf chickens can lay normal sized eggs, that is if over many generations the offspring have been selectively breed to produce larger eggs.
In my post, there is a difference in size between bantams and dwarfs. Dwarfs just have to be smaller than normal (for example 10-40%) while bantam size is different. Bantam size is due to a number of genes producing a very small bird.
I covered a lot of information; if you have questions, feel free to ask and I will do my best to answer the question.
