advice welcome

Hi everyone I really need help,  

I had sex beginning of June (don't have a partner that's how I remember lol)I was due my AF on 8/6/16 but didn't get until the 20/6/16 so was 12 days late,it lasted a day then off a day & on for 3, I'm usually very heavy but not this time.  I was due this month last week and still nothing 😕 my tummy feels different and I now have a white discharge  (TMI  sorry lol ) I keep getting negative tests,  when my AF is due I keep feeling the usual (dragging on tummy, hungry etc )this time I'm so tired and cranky, hungry all the time,  got docs next Thurs but can't help panicking,  I don't mind if I am as I would love another child  (have a 7 year old son to ex hubby)

Thanks