Late period / negative test

Regi
Ok girls need help we are trying to get a BFP but I don't know what this means I got my period normal last month my period is 4 days long cycle period is 26 and I got it Feb.25-28 and since then I have not got it I took two test today and it's a no but I know I'm going 3 days late. am I doing something wrong ?or how long do I need to wait?