Confusing period

Okay so my periods have been the same my whole life, I’m 23 by the way. Last month (June) I was to get my period on the 16th. I didn’t get it till the 19th but it was literally for about 4 hours then it went away for a whole day and then on the 21st it came back all day but was gone when I woke up. Then I got another half day period July 2nd. I’m totally confused. I took two pregnancy tests and they both said negative!