Thank heavens for choices.
Edited by LillianB - 10/31/11 at 6:49pm
Another option would be to have an IUD placed. If Paragard (the copper iud) is placed within 5 days of unprotected sex it is 99% effective in preventing pregnancy. Then you also wouldn't have to worry about birth control until you're ready to get pg again. It's more expensive than Plan B obviously.
Just because the OPK is negative today doesn't mean it mightn't be positive tomorrow or the next day, and Plan B is more effective if you take it sooner. I'd go for the Plan B or the IUD like the PP mentioned. Plan B will probably make the rest of your cycle kind of wonky, so be prepared for your chart to be garbagey.