Please respond to this

My period is now 4 days late, I have not tested yet due to work and moving so I haven’t had time. Last night while my SO and I were at dinner, I had a small amount of blood (the color of AF) when I wiped so I put a pad on, thought for sure I was out. However, that was it! It’s now been about 12 hours and still no AF! Has this ever happened to anyone and it turned out they were pregnant? Or is this AF? Also, the picture is from the day of my expected AF. Could that have been implantation?