So am I pregnant

So something weird just happened. Idk if it was implantation. I'm not suppose to start my period until tomorrow so I had sex this morning with the hubby and I noticed spotting after sex when I wiped so I thought oh boy here she comes put on a pad one drop of blood and when I wipe now she's gone. We are trying to conceive and got busy during my fertile week. Normally when I have sex to bring on my period it comes on it never just goes away. But could it just come back on tomorrow or was that implantation.