I'm scared to get excited!

AF is 3 days late..I've been monitoring my cycle for a year and it's only been a few days late ONCE, usually right on time. I'm hesitant as this was literally our FIRST time TTC...how can I know if it may be a chemical preg vs it's time to get excited!? The only symptoms I have are intermittent cramps and small amt of discharge. Please help my nerves! TIA