Don't know what to think...

My last shot of depo was May 2014, so it's been a year. Since March my periods have been regular and showing up on the 7th or 8th.. this month it doesn't seem like AF is going to show up. We've been using preseed and BD every other day. I've taken tests and all negative and one test I'm pretty sure there's an indent. Is there still a good chance I'm pregnant? I've been naseous, beyond tired, and has thick white CM.