missed my period!!!

Ok so I was suppose to get my AF on 9-16-16 but didn't and I took a hpt on 9-18-16 and it was negative I still haven't gotten my AF but on the 18th I started to spot very little a pinkish brownish color! I'm currently 6 days late and still no period! What can be happening?!??' Also I have been TTC for 2 1/2 years was on clomid for 6 treatment tries but nothing and I have been getting my AF every month this year 😬😬🙈🙈