I would suggest to continue doing research on this as a business venture. IN the meantime if you are able to do this for some people, go for it. Certifications or degrees in event planning only help clients know that you are serious about your business and show that you are legitimate.
I myself have done a lot of research and I am taking an online course to be a certified wedding consultant. I fell into it in a similar way that you did in helping a friend with her wedding.
You may want to see if there is an online certificate course that you can take in your own time and may be better for your budget.
Then you want to get a business plan together. There are plenty of examples online. Score and the small business administration also have lots of good information.
You should also research the base market in your area to see if this is a service that people would be interested in. Then once you have all that together you can start marketing your services.
Personally I would have loved to have someone like you when I was planning my sons birthday. I seem to be great at helping other people plan events, but horrible when it comes to my own events! (plus it stresses me out!)
One more idea, you may want to contact places like Bouce U, Chuck E Cheese, Incredble Pizza etc. and see if they would partner with you and if you could get any special deals for potential clients.
Good luck I think it's a great idea!