12 days late, 2 negative PTs. Pregnant or cycle change?

Deleted. • This app is absolute garbage and so are the people on it.
So I have a feeling that I've basically stressed myself late. I spotted light brown with dark brown clots from October 5th to about October 12th or 13th and I was supposed to get my period on October 15th and it never came. I'm now 12 days late and I'm freaking myself out. 
I took a test in the afternoon of my 6th day late and in the morning of my 7th day late. Both were solid negatives. I plan on testing again tomorrow morning. 
I feel like when I started spotting all that old blood, the thought of implantation bleeding popped into my head and freaked me out so bad that I expected my period so much and that's what made me late. 
Last month, I had sex with my BF on September 7th and then I got my period on time (Sept 15th). We didn't have sex again until October 2nd, which was the last day of my fertile window. Both of those times (and then again on October 7th) we had sex starting out without a condom but put one on in the middle. That all doesn't add up to the spotting being IB, but it still freaked me out. We are not TTC and I'm not currently on BC.
Maybe my cycle is changing? Since summer, I've been extremely inactive and I don't get out very much at all. My sleeping pattern has changed and I sleep a lot later than I did in the spring. Also, I barely eat anything home cooked anymore. Mostly restaurant food and fast food. I also have been smoking (cigarettes) more than I ever have before (sometimes 5 cigarettes a day, as apposed to just one; I don't smoke much, but it's still a considerable difference). I've also been extremely stresse and I've gained about 30 pounds in the last three years (170 as apposed to 140). 
I feel like all these factors are more reason for me to miss a period and the chances of me being pregnant are very slim. 
Sorry this was so long. What do you think?