The important thing to consider is what discipline you are most interested in. If that happens to the historical discipline, then be welcome to attempt it. I myself am a history major and do well in the subject. Though for you, you would decide whether or not it may work for you.
Having a somewhat limited range of history is not necessarily something that can prevent you from it. The historical discipline, especially as you move to latter years tends to open up more to focus on subareas of specialty within the discipline.
In regards to teacher and testing, you should consult what ever academic services your university may have. Furthermore, if you are interested in history, you could try to arrange a meeting with one of the history professors to get more information on the possibility.
Also, the possibilities of a history degree are not just limited to the possibility of being a history teacher. In case you may be worried about job options. The skills which are involved with history (researching, writing, critical thinking, and argumentation) are skills which can be useful and marketable to many types of jobs, so long as you know how to market them. Many who take undergraduate history degrees go on to law school.