period

hi, everyone im worried i wont be getting my period this month and i need it to start my ivf cycle my last period was 8-22-08 and i got it with provera i been on provera for the past 4 cycles i been having cramps since sunday 9-21-08 but i have them stronger today 9-24-08 but no period no brown discharge or nothing but i been having cramps in my like pelvic area and also on my back and kind of on my ovaries so i was woundering if cramping means that im going to be getting it anytime this week???? and im also on provera i started on sunday 9-21-08 so im on my 4th pill and cramping thanks so much