What Causes Delayed Periods And Lactation After Having The Tubes Tied?

I am 35 years old. I had a tubal ligation when i was 23 yrs old where they cauterized my tubes since i had 2 high risk pregnancies previously which were live births. I have epillepsy and take Depakote 750 mg BID. I am concerned because my last menstrual cycle was 2/14/10 - 2/19/10 and I havent had one since. My husband and I have no reason to use birth control. Today, I began lactating from my left breast and now i'm worried