TTC for 6 months

Hannah • Married with a 3 year old daughter who`s begging to be a sister!
My husband and I have been trying to  conceive for 6 months now. Every month is a bfn and af is always on time. Last month af came 9 days early and only last for 3 days being very light. Took a test and bfn. I'm so confused bc I just knew I was pregnant.. Anyway, just curious to see if anyone has had this problem..