2 missed periods and negative results

At the end of March was when I had my last period I was due on 2 days ago and haven't seen blood, I have an app that shows me when I am on next and the app is correct every time, when I missed my period the first time I done 2 pregnancy tests and they both was negative a week later I done 2 more and they was still negative, I am now 2 days late and have done more tests that again came out negative, I am having pregnancy symptoms and my doctors say that there is a possibility that I am pregnant so they have done a blood test on me, I just wanted to know if people have experienced something like this before, it's starting to worry me that if I'm not pregnant there's something wrong with my body, I just want to hear people experiences if this sounds similar to yours