I am so excited that you are interested in engineering. To aid in your decision I have put a couple of suggestions below.
1. First I would encourage you to write a list of pros and cons about each discipline to help you see what you are really passionate about.
2. For engineering know that you will use math and science a lot in all your classes so you must have some interest in those subjects which you have already mentioned. Know that anything you do takes hard work.
3. It is still possible to teach in engineering if you so desire. I am currently working on my PhD and after this I plan on becoming a Professor at a University. It is possible to teach with a M.S. degree at University as well it just depends on what you want to do. But, if you just want to teach elementary or high school then I encourage to find a subject you like and to take the education track.
**Just think what do I see myself doing for a long time that I am passionate about or love doing! Then you will find your answer! If you have anymore questions just ask.**