I'm kind of the same way. I am already to go again after less than two months postpartum. So then I do use charts and temp checks.
My youngest is almost two and I stopped charting last summer. I still would like to wait a bit longer, but it would be fine if baby number three showed up any time now. So I am not taking it as seriously now. It's nice to have that kind of freedom.
We love the freedom. Of course, many of our friends have 10 kids so we're under pressure to "catch up". Ha! I don't think we'll make it that far. We started late and a few miscarriages put us behind.