Repost from TTC - could this be it?

This may be TMI...I'm not TTC, but I may have anyway...

My cycles have been irregular for the past few months since coming off Depo in August for medical reasons. However, my AF has been trending longer from 1.5 weeks, to 2, then the last time 3 weeks.

I was exactly on week 2 when I had very mild spotting and mild cramping for 1/2 a day, enough to get really frustrated, thinking that AF was coming again on week 2. Then nothing came.

It's now 4 days later and absolutely nothing other than b tenderness.

Could this be conception and how long should I wait to find out? If I am PG, what should I be doing differently?

This wouldn't be a bad thing, just a little off on life's timing...but it would still be a happy surprise

Thanks ladies!