Hi Diane and welcome,
Every symptom you mentioned, including the dizziness, has been reported here by other thal minors. Yet, almost every doctor will give you the same litany...mild anemia at most and no symptoms. Well, the doctors are quite wrong on this and the reason they are is because they are simply repeating what they have read in the texts. This is not based on experience with thal minor patients. And obviously if they have such a hard time recognizing thal minor, they don't have much personal experience with the condition.
The reason it is not easily diagnosed is that most doctors automatically think iron deficiency when they see anemia and don't even run the proper iron studies that can determine iron deficiency. An examination of red blood cells under a microscope can usually show the small irregular red cells associated with thal minor. Further testing, such as hemoglobin electrophoresis can verify the diagnosis.
Please do what Canadian Family has suggested and read through the wealth of information on thal minor that we have on this site. And pay special attention to the advice to educate your children about their carrier status so they can avoid having thal major children with another carrier. If there is any piece of advice you should listen to in your entire life, it is that. Major can easily be prevented by making carriers aware of their status and the risks but only if carriers take this seriously. Most parents would not willingly put their children through life as a thal major and will tell you if they had only known, they would have proceeded much differently.