OPK as pregnancy test

So every time I take a test its negative and I'm over a week and a half late and don't know what to do now. I'm having constant nausea and I had some spotting about 3-4 days before AF was supposed to visit but no actual bleeding. My breast are starting to get a little sore and I'm constantly tired. And depending on the day I'm either really hungry or not hungry at all. So can I use an OPK as a sort of pregnancy test?