Yes, the IUD is generally permissible in cases such as yours. There is no halachic preference for Mirena over the copper IUD at this point in time, since both are considered safe and efficacious.
In choosing between them, please note that the Mirena IUD often leads to staining for a few months after insertion. Such staining can make a woman niddah or invalidate her clean days. After the staining subsides, however, a woman with Mirena may not have bleeding for years.
The copper IUD may lead to staining at the very beginning of use. Some women also experience irregular bleeding, heavier and/or longer menses, and changes in the length of the menstrual cycle. These changes may subside after the initial adjustment period, or continue for the duration of use.
It is impossible to predict in advance exactly how an individual woman will react to either type of IUD.
Please refer back to our posted questions and articles for more discussion. It is important to review the laws of stains, and to be prepared to ask halachic questions, in order to minimize the halachic difficulties that may accompany the adjustment to the IUD.
Behatzlachah! Please don’t hesitate to be in touch with any further questions.