Is Irregular Menstruation After Tubal Ligation Normal?

Hello....I was concerned because I have Children...my first was born by c-section and so was my second..my Third was also born by c-section and I was immediately got my tubes ties in the operating room...two years has pasted and I was having regular menstrual cycles for the first year then then were irregular now it has been almost2 months and no menstrual cycle..I am getting worried is this normal and could I be pregnant?