You may just be experiencing a lighter than usual period. If you have had unprotected intercourse then I would advise taking a home pregnancy test about a week after you were due your period to be sure. It would also be a good idea to check with your Dr so he can run a blood test. Sometimes our cycles can go out of whack or alter slightly and this can be caused by stress, illness, medications etc.
I'm going thru the same thing...Off Provera April 18th and started spotting April 22nd and still spotting today(18th-22nd). What is really going on....I just want my period to come on and go off. I start my Provera again May 1st.