What happened?

So I am usually very regular and have not had a period since March 20. A few days after my period was due (April 19) I took a test and it was negative. Life happened and I went on vacation, I came back on the 30th, and took another test that showed a VERY faint line. The next two days I took a test again and it had not gotten dark whatsoever. I made an appointment and my urine test was negative as well as the blood test. Could this be a chemical pregnancy? When should I expect my period to start again?