Help me understand please...

I missed my period 4/13 and today is 4/21 since then I’ve taken 4 tests (saved only three) and all of them are negative. I’m not on any medication, I don’t drink, I don’t smoke, and I’m not stressed (at least I don’t think I am) but I noticed that there are no signs of my period coming so has this happened to anyone?...can you beautiful ladies help?

PS- being pregnant would be wonderful, my son is 4 and he wants a sister/brother. He’s already asked me dozens of times. I do know that you all aren’t physicians I just wanted to know your experiences. Thanks.