No AF yet, 16dpo but BFN

Not sure if IUI#3 worked out.
I have a bad non-stop twitching above my left ear for more than 1 day. Don’t think it is a pregnancy symptom but maybe stress.
I just don’t get it, I was married 3 times in the past 21 years, never used the pill, never avoided pregnancy, in the past 2 years have actively tried to get pregnant using ovulation tests. All hormones are fine, no physical limitations, regular periods, and I don’t get pregnant

I am 40 now, so probably the egg quality is declining. I am collecting the tips I have seen in the forum and will try to apply. It is just frustrating not to know what else to do to have a healthy baby in my arms
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