Re: Is it possible?
My teachers tell me that one of Ki Society's senior instructors didn't start aikido until he was 48. I find this very encouraging (I was 39 myself, and sometimes wonder if I will live long enough to be any good at it....) It seems that aikido is not like gymnastics or figure skating, where if you don't start as a child you will never be excellent at it. You can definitely reach excellence starting as an adult.
If you passionately want to teach, you may wish to choose your dojo on that basis, or seek out opportunities to learn to teach aikido--it only partially overlaps with learning to do aikido. One of my instructors did a year-long teachers' training in Japan, and she definitely has a much richer set of instructional skills for it, as well as remarkable eye for assessing students' technique. Some dojo put a heavy emphasis on learning to teach, others don't, and if that is a major focus for you, it's worth searching out.