Help 15 days late

So I posted this on gerneral pregnancy already thought I would post it on here too. I'm 15 days late. I've gotten 3 BFN. I haven't tested since I was 7 days late but will test again tomorrow and at the end of the week. My mom didn't get a positive test till she was 8 weeks with my brother. Wondering if I'm like her? Has this ever happened to any of you? I have almost all the pregnancy synthoms. My boobs are super sore and I stay bloated and don't feel like I'm going to start my AF. I have cramps but they're definitely not period cramps. My last AF was august 1st, the month before that July 2nd and the month before that June 3rd. I stay on a regular schedule. Just thought I could use some insight. Please help if you can relate at ALL! Thank you  :)