Could Missing Of Two Consequent Periods Normal While On Qlaira Pills?

I was on the depo provera 4 5 years, i took my last injection in april 2010, i got my period back in november 2010 & started the Qlaira pill, ive just started my 3rd wallet and still have got no period, ive read the info booklet and it says missed periods are common but not 2 in a row, could i b pregnant?