I'm not pregnant, am I?

So, I took a pregnancy test on Friday, May 6th and it was negative. After feeling quite symptomatic for early pregnancy signs, ie nausea, lethargy, nasal edema, I retook a test on Wed, May 11. It was positive. Then on Friday, May 13, I started what seemed like a normal period. So, today May 18th, I took a pregnancy test and it was negative. So, I would suppose I'm not pregnant, but now heart broken. Is there any room for hope? Should I still go get a blood test in early June?