How do I run an event on my own without getting overwhelmed?

You can help with an event, but running one yourself overwhelms you, and that jump is real. Helping means holding one piece while someone else holds the whole; running it means holding the whole, and the whole is always more than the sum of its parts. Feeling swamped the first times is normal, not a sign you are not ready. The overwhelm mostly comes from trying to keep the entire event in your mind at once. The fix is to get it out of your mind and onto paper: a timeline of what happens when, a checklist of what must be done before, and a list of who is responsible for what. The event stops living in your head and starts living on a plan you can follow. For the next one, build that plan early and lean on it instead of your memory. Break the whole into a sequence of small, dated tasks and do them one at a time. Running an event is not one huge act. It is many small ones, arranged in order.