What is going on?

Since we didn't trigger and do the IUI, I'm not exactly sure if/when I ovulated, so not sure when AF will rear her ugly self. The BD ban was off Monday and we BD last night. I woke up this morning with brown spotting. Of course the crazy side of me thought, "implantation spotting!". We did BD 2-3 days prior to the day I think I O'd. I'm trying to keep myself from getting too hopeful. I mean, why would something like this happen to me, when it can't even happen when we try really hard?!