Hi Grace
I'm not a doctor, and in my humble and totally non-medical opinion, I don't think the surgeries should have caused your periods to stop. Unless they removed your ovaries, you should still be having periods. The only thing I can think of is that perhaps the surgeries have really thrown your cycle out of whack.
I would definitely get with your OB/GYN and disucss this with him/her. I don't think there is anything to worry about, but again, I'm not the doctor and it would obviously make you less anxious if you knew what was going on. It's always the smart thing to do to bring anything abnormal to your doctor's attention.
Peace
Greenlydia