That could be very true. I've also heard that if you just keep having kids it's easier to conceive when you are older. So first one at 20, tenth at 40 and it's easy, where first at 40 is nearly impossible.

doesn't have scented anything in the house (FDA doesn't regulate scents),

This is a huge Trojan horse for unregulated, untested chemical cocktails entering the home. There is literally no safety testing or requirements for chemicals added for 'fragrance.' In fact, they don't even have to disclose what chemicals are used, just "fragrance." And you can't even keep it out of your house because you're guaranteed to have neighbors who are fumigating the neighborhood with their dryer vents ejecting chemicals from their scent pods and dryer sheets and heavily perfumed laundry soap.

Most people are walking around like zombies with no idea how badly they're poisoning themselves on a daily basis because their noses are desensitized from being bombarded all the time. Every day I encounter people whose clothing smells so powerfully of their chemical laundry soaps that I can't even be in the same room with them, and they have no idea they're just breathing those chemicals in with every breath, every waking and sleeping moment. The chemicals are so persistent that even walking through a neighborhood where someone's dryer vent is spewing this stink will cause my clothes to start smelling like that.

Try and eliminate artificial scents from your life for a month and watch what happens. Get unscented laundry detergent, hand soaps, dish soaps, fabric softeners. You'll be amazed when your nose starts to recover and you can really smell things again. You'll be amazed at the stench of chemical perfume soup all around you, and the laundry soap aisle at the grocery store will be instant headache, but it's worth not poisoning yourself and your family.

"I'm confident it's the food we eat and the artificial chemical shit we fill our lives with on a daily basis that causes women to not be able to conceive past ~35."

External factors like general bodily health, level of exposure to pollutants and food, will definitely impact the hereditary fertility, but there are numerous factors; an important one is base geonome and the compatibility between the male and females do.

Optimal female fertility is again very individual, as many factors are in play, not least that the body should be well suited to bear and deliver the offspring.

I believe that nature hard coded limits for fertility, as the rules that generally apply everywhere in the animal kingdom, are quite similar cross species..