No period in July Negative tests.. Confused

Hi ladies some help please

I should of had Af on the 17th July but nothing appeared so i tested still negative gave it a few more weeks and tested yesterday still negative! No symptoms of Af coming and no symptoms really of pregnancy only feeling a tad sick. Ive tried booking into the my doctors which are absolutely ridiculous tell you to ring at 8 in the morning so I do they answer at 2 mins past 8 and no appointments left?! How?! So I'm annoyed and dunno what to do loads of things going through my head... Could I still be pregnant? Is there something seriously wrong?

I had a miscarriage in Feb 2015 and been trying ever since but nothing 😢😢

Please help me advice xx