Missed period

I'm kinda confused cause I haven't been pregnant in 8 years. After my daughter and having the depo shot I really didn't think I could get pregnant.. well I have two apps download for my period tracker. This one and another one.. this one I am 8 days late on the other I am 10 days late on. My boobs are extra tender on me. And I been getting sick to my stomach for the last two maybe three days at around 6pm.. and I am at work tonight and had to talk myself out of wanting to throw up while taking the pictures for the load I had to send out.. I'm kinda a little confused cause I have took two dollars tests and they came out negative.. I know some people they don't work on.. could I be pregnant are is my mind playing tricks on me and I'll get my period soon..