Do I still have a chance

Walker bait • Mother of 3 wonderful kids, my middle child is epileptic and has ASD so I`m a stay at home mom I have been with my husband for almost 7 yrs but only married for 2 yrs. And as happy as can be.
Ok so the last time I had sex was back in June, the last couple months have been very exhausting for me I'm always tired and sleeping alot. I have been very regular this yr and I had my period june and july but now im 4 days late nothing has changed in my life style except sleeping more often. But my hpt came back negative has anyone gone threw anything like this and found out later they were pregnant all along thanks in advance.