Agree with getdown and iheart - I had one child with fertility treatment at age 42, and tried for a second (with fertility treatment) at age 44.
I had half a dozen sessions with an osteopath who specialises in fertility. He gave me some advice that helped me focus, when he advised that I do everything I possibly could to conceive within a specific time frame, but to pick a 'stopping point'.
He had witnessed (and assisted) many women who became driven to the point of obsession about wanting a second/third/etc child. The desire consumed their time, their emotional energy and their bank accounts - and definitely interfered with their ability to fully enjoy the family they already had.
I was unfortunately not able to have a second child - and of course, have 'what if' moments, and sometimes wonder if I didn't try hard enough or long enough. Or if I should have ventured further into the realm of scientific assistance/intervention to have a second dhild. There is always the thought that 'just one more' try of IVF or differerent fertility drugs/dosage might have done the trick, or maybe if I'd had fertility reflexology or meditation, or , or, or. It can go on forever.
But the words of that doctor helped me immensely - in the immortal words of the Stones "you can't always get what you want".
A bit flippant perhaps, but accepting that is a huge life lesson.
And in the meantime, I enjoy my miracle daughter and am grateful for her every day.