If you are not ready to make a decision that you are certain that you do not want a permanent decision, then sterilization is not really an option. However, the most common approach for a woman that is certain that she does not want any further children is sterilization. Sterilization can be done of either member of the couple, but it is easier and less risky to perform a vasectomy than a tubal ligation. Sterilization is even more desirable in a woman that smokes or has other risk factor for blood clots or cardiovascular disease.
It is important to note that the majority of men that are afraid of having a vasectomy are actually afraid of complications that are not really a concern. Since you are a nurse, you have a better understanding of surgical risk than most women, but the risks of a vasectomy are quite low.
There also is a newer technology to perform non-surgical sterilization, such as Essure. This is a device that is inserted into the opening of the tubes and can be done as an office procedure. Since it is a relatively new procedure, we are still learning about the long-term effects, but when you get to the point that you are wanting to consider a permanent intervention, then you can also consider this as an alternative to a traditional surgical sterilization.
In terms of reversible contraception, as you get older, the risk associated with smoking and migraines will only get greater. The level of concern in using hormonal contraceptives become greater with each year. The most effective form of non-hormonal reversible contraception would be a copper IUD. Any IUD can be associated with abnormal bleeding patterns, and it appears that you experienced this previously. Another option for reversible contraception would be a diaphragm. When used correctly, diaphragms can be very effective. They are not as effective as IUD or hormonal methods, but is far more effective than condoms. If you do not want to repeat the risk of potential side effects of IUDs, then it would be appropriate to consider a diaphragm.
However, once you are certain that a permanent solution would be appropriate for you, it would be most effective and lowest risk to consider vasectomy or tubal ligation.
If I can provide any additional information, please let me know.