pregnant? irregularity?

I had my handsome boy on May 13th of this year. I got my period on July 4th for the first time, and got my period the second time on August 3rd. However, it's September 6th and no period... my August third period seemed short and light 
On August 16th - I had light pink and then brown spotting for 2-3 days. Which sounds like implantation bleeding - but my husband has been pulling out like he usually does and always had before. 
I'm been stressing about this since September 2nd when I didn't get early cramping or zits. And I've woken up with heartburn. I'm exhausted - but then again - I do have a four month old... and just started a new job. 
I have taken several pregnancy tests. Here are what they look like. 
Any help or stories like this would be greatly appreciated! 
I can not fathom the idea of being pregnant again...