Could i still get my BFP

Hello lovely ladies. I went to the doctor yesterday to have a urine pregnancy test done, before I took my hot,in fear of getting a BFN.well the urine test they did came back BFN.😯. AF was supposed to be here 4/20 and she still had not came.my question is,am I positively out this month or could my body just have not built up enough of the pregnancy hormone? Has this happened to anyone else and then got a BFP?