I'm also not a lawyer, but don't let that stop me from offering advice...
There's a old trick known as a "poor man's patent."
Basically, you make a copy of all the details and drawings and notes and pics of protypes and everything else related to the development of your gizmo, seal them in an envelope and mail it to yourself via USPS registered
mail. (Not FedEx). When you get it back in the mail - LEAVE IT SEALED and file it away where you can find it years later. The seal and the cancellation dates "prove" when
you had the idea.
I don't know how well this trick would stand up against a high powered law firm that's defending the dirt bag who got rich on your idea. In short, you pay a lawyer up front to keep you out of trouble, or in the end to get you out of trouble. Or you just give up and give out.
Good luck! I hope whatever you're up to works out well for you.