E.F.
I would look into either Paraguard (the copper iud) or Mirena (plastic IUC). Both last 5 years-- Paraguard is totally hormone-free, but can lead to very heavy periods, Mierena (which I have) has a tiny bit of hormone (way less than pills, etc) and I haven't had a period since I had it put in 14 months ago. The Nuva Ring (which has a low amount of hormones too) might be another option, and the new diaphrams (totally hormone free) are supposed to be more convenient, though I haven't used it. Talk to your gyno-- there are TONS of options.
The old joke is "you know what you call people who practice natural family planning? Mom." It CAN be effective, if your biology is very regular and you are VERY, VERY careful about it, but if it would be a disaster for you to have another kid, I would use it in conjunction with another method... best of luck.