Mazal tov on the recent birth of your baby!
If we understand you correctly, you are debating whether to keep the copper IUD and give it a chance, or have it removed and look for a different form of birth control. It is so important to discuss with your health care provider the different types of birth control and the possible side effects. You must explain how mid-cycle bleeding (which may be medically insignificant) has a serious impact on your life. Therefore, this is an important factor in choosing your method of birth control. You can refer your physician to our sister site for medical professionals, www.jewishwomenshealth.org. The site is designed to assist health care professionals in providing optimal care to patients who observe hilchot niddah.
At this point, the staining you are experiencing may well be from the depo-provera and may continue for the next 6 weeks or more, even if you decide to remove the IUD. Therefore, since this period will overlap with the initial adjustment period to the IUD, it is probably best to keep in the current IUD. Further, while the copper IUD often has an adjustment period of up to 3 months in which a woman may experience mid-cycle bleeding, not all women have a difficult adjustment; a certain percent see improvement after one or two months. Many women are able to become tehorah in this period, and then avoid becoming niddah from any further staining by wearing colored underwear and avoid looking at toilet paper after urinating. (Please read our article on stains for more details.) As you pointed out, some women also experience heavier periods or irregular bleeding even after the adjustment period. It is impossible to determine in advance how the IUD will affect you. Speak to your physician about taking ibuprofen or other medication to help reduce the bleeding.
Mirena can have an even longer adjustment period than a copper IUD, and some women experience staining for up to 6 months. Again, not all women experience this adjustment. Those that do have staining may be able to avoid becoming niddah by taking precautions against stains as outlined in the article above. Further, after 6-12 months many women cease menstruating completely. While Mirena, depo-provera, and the mini-pill all use progesterone to prevent pregnancy, they all affect the body in different ways. Particularly, depo-provera is a larger, sustained release dose, as opposed to the mini-pill which is taken once per day and the Mirena which is released locally into the uterus. You can not determine how your body will react to the Mirena based on the depo-provera.
For women who are not prepared to deal with a possible adjustment period to any of the methods above, we recommend considering a diaphragm until you finish breastfeeding. While it is not as effective as hormonal methods or the IUD, when used correctly with spermicide it is 95-98% effective. Even if you decide to switch to the Mirena or a different form of hormonal contraception, you may also wish to consider using a diaphragm and spermicide as a temporary method of birth control to allow yourself to recuperate physically and emotionally from the stress of this extended niddah period.
Alternatively, using a regular combined progesterone-estrogen birth control pill is another option. Although there may be an adjustment period of up to 2-3 cycles (as with any hormonal contraception), afterwards staining generally ceases. While this is not the preferred form of contraception while breastfeeding, many women are able to use this method without a significant decrease of the milk supply. For more information you can read our question posted on the site on this topic.
You should keep trying to complete the taharah process. Speak to your rabbi about reducing the number of bedikot required. Be sure to bring any questionable stains for evaluation. You should also change your underwear more frequently to prevent any stain from accumulating to the size of a gris (the size of a US dime or Israeli shekel). If the staining persists, you should discuss with your physician the possibility of temporary hormonal intervention to relieve the staining. Once you are able to immerse, take precautions against becoming niddah from any further staining as outlined in our article on stains above.
Please discuss all your options with your physician to make an informed decision about your method of birth control. You can read our article on choosing a birth control method for more information.
Please feel free to get back to us with any further questions.