Everything's "normal"

Here we are, at week 19 with all test results coming back "normal". This is shaping up to be similar to my pregnancy with Mia, only minus the pain from the gallstones (had that sucker removed last year). Now we wrestle with another matter, one that I cannot believe I am facing. What do we do AFTER this baby is born to make sure it is our last?
That sounds crazy, coming from someone who worked so hard for a year to get pregnant. But those memories are fresh. I don't ever want to go through this again. I don't want to temp, have to pee on a stick, or face these nerve-wracking doctors appointments and ultrasounds.
The kink in this is that our health insurance does not cover birth control, although my sister claims that it paid for her IUD (she and Chad have the same employer). The alternative to shelling out great sums of money out of pocket for the rest of my child-bearing years is of course more permanant. I will be having this baby by a planned c-section and my OB is willing to do a tubal ligation at the same time, as long as I am 100% sure.
When I brought this up with Chad, his first response was, "is it reversible?" OK, I said, there is our answer right there. Even the fact that you are thinking about future children tells me that we can't do this. Dr. Eichenlaub agreed. He said, "you guys can't even be 99.5% on this. I need 100%."
But knowing the worst case scenarios that are possible, I am afraid something bad will happen and I will end up feeling it was a mistake. I told Chad that I feel like I am messing around with God a little bit. What if something happens with this baby? What if I lose a child? There goes my chance to have another. But then I think that no child is ever a replacement for another; certainly after a miscarriage I understand that.
So I go back to that feeling of never wanting to be pregnant again. And the anxiety circle begins again.
I am hoping that I feel better after my 20 week ultrasound next week and feel like I have some answers.