Is something wrong??

So all the way up until March I was having my period around the 20th. Then in March I had no period. Then in April I had one that started on the 3rd and went to the 8th. Now it's May and I'm not having a period again. Tests have been negative, but maybe I was testing way to early. When should I have expected my period in your opinion? Around the 10th or around the 20th?? Could I still have a chance of pregnancy???