Hi Isuru,
It's possible to have both thal minor and iron deficiency (IDA). They are not related, but will have a cumulative effect on anemia, but only the IDA can be treated. Does she have a history of anemia or is it more recent that she has become so weak? If it is recent, correcting the IDA should return her to her previous energy level.
As long as it is certain that you do not carry thalassemia, children that the two of you have will either be non-carriers or thal minors. They cannot be thal major unless both parents are carriers.