Depressed about my thinning hair/ prenatal vitamins/ evening primrose?

I'm 44 and for every year my hair is thinner, not only on the top but my ponytail is so thin.

I have tried hair vitamins but so far nothing helped. I was reading that prenatal vitamins are good for the hair and wondering if it worked for you. I'm looking for one that has a good amount of iron because mine is on the low side.

I've been on Armour thyroid for years. Has anyone heard of evening primrose for hair?

I hate to take iron supplements, bad on my stomach and constipating.