Tubal litigation/pregnancy

I have three kids..all boys..and a step daughter. My second son was conceived while using condoms, I had gotten pregnant with an iud in a couple years ago miscarried when they removed it, and got pregnant on the pill with my youngest who is two months old now. My husband and I do not want anymore kids. I got a tubal litigation done when this one was born and I'm also breast feeding. I keep having dreams that I'm pregnant. I'm so scared of still getting pregnant. I was told by my Dr it's like a 1/1000 chance of getting pregnant..that seems pretty high to me. Have any of you ever gotten pregnant after a tubal??