Bad planning? Planb is called planb because it is not "plan a". That means a woman must have a "plan a" to prevent pregnancy if she does not want to become pregnant. A "plan a" can be birth control pills, diaphragm, implant, iud, condoms, no sex, etc... Planb is for use on rare occasions (that's the idea). A woman who uses planb many times can talk with her primary doctor about living a better planned life.
No. While I completely agree with the previous answer that you need a plan a, having taken Plan B several times should not prevent you from getting pregnant in the future. Certainly taking Plan B can throw off your cycles for a bit, but your cycles should regulate again and you should be able to get pregnant. If you do have trouble getting pregnant in the future, it's not from the plan b.