Missed period but negative test

I missed my period by almost 3 days but took a test and not pregnant

Mind you I never have irregular periods my periods always come on time

I have a 9 month old daughter and the only time I missed my period was when I got pregnant with her after her my periods went back to normal the same starting day as before my pregnancy and everything...

Please help/advice

Update: lol it was me getting off of birth control that was making me late I finally got my period a month later😅