Hey guys I'm

Wondering if anybody has ever taken a pregnancy test come out negative but then took it again later and it came out positive . Today is the 13th day after unprotected sex I cannot wait until a missed period bcs I gave birth couple months ago and still haven't gotten my period since before. I took th test this morning was it too early? I feel like I am pregnant I just know it but the test came back negative when should I give it another try?