Missed period but negative hpt 😐

If anyone has experienced this or has any insite, I'd really like to hear about it! 

My period is never late and if it is, it's no more than 3 days late. And I always have the usual pms symtoms. I have a six and five year old and got positive hpt's with both on the first try. Now, I stopped taking the pill since I got my period in April and was due to get it May 29th. It's been almost 9 days and I've been super queasy, (which i never had with my older two) and feeling bloated and tired. Took two tests yesterday, first one I got a question mark and second one was a negative. What the heck?!?!!