You did show those things, but you haven't shown any causal relationship between those three points, only a correlation.
You can argue that the second and third are substantiated with some of the evidence, but the first has only been connected with being older, not directly with the risk of infertility.
"30 is the age where women start to feel old because they can't compete with 20 year old girls." is not a substantiated conclusion.
"30 is the age where women are less fertile than before" is correct. But the same can be said of 29 from 28, 28 from 27, etc.
At no point have you shown that women feel old at that point- nor have you shown any 'causation' (you used the word because) between the ability to compete with 20 year old girls and this feeling of being old.
It is a potential hypothesis- but without further data, the hypothesis is no more valid than a competing hypothesis, for which I will construct one.
Being older:
-Less sex appeal
-More risk of having children with diseases
-More risk of being infertile
From this data, I provide the following hypothesis. As a woman ages, fertility decreases due to the gradual decrease in hormones related to fertility.
There's a higher risk of having children with diseases as women who are older have had more encounters with physically strenuous or mentally taxing situations. This could be that stress, mentally or physically, over a lifetime can increase chance of complication for childbirth.
Women who are older have less sex appeal, possibly due to a gradual decrease in skin purity and symmetry, both of which are psychologically favored as facets of beauty. Hence, having those features would be the cause of more sex appeal, rather than simply being young being the cause.
These are all different explanations that haven't been shot down, that can describe the same phenomena. Please, show how your phenomena are linked in a causatory fashion.