How do I get started with this?

Long story, but I need some help! I've always wanted to be a teacher, ever since I was young. However, while I was in college studying to be an elementary school teacher, I started working at a daycare and I realized that I am not great at making lesson plans, AT ALL. Not sure if it's something that I could get better at, or I'm doomed to be terrible at it. I've recently started using a planner and gone crazy with keeping things organized and I've realized how much I love doing things like that. I figure an administrative assistant would be a good way to go, however, as I was about to start school again to get a degree and become a medical administrative assistant, I thought to myself "I don't want to be in the medical field in any way, shape, or form, I just would not be happy." I want to work in a school setting, so I really believe that I would enjoy being an administrative assistant in a school. I'm not sure what the official title is for this job, so if someone could enlighten me, please do. My question is, (for teachers) do you get better at lesson planning? I enjoy it, but it's so hard for me to come up with things. Not only that, but when I finally started doing the classes related to my major, I failed them or barely passed (they were online classes, I do better in a physical classroom). My other question is, how do I go about getting a job in a school office? What kind of degree would I need to get? Sorry for the length, but I really want to be happy with my job and I want to get everything figured out and graduate so I can start my family. Thank you in advance!