Sounds like you're well under way. I'm glad to see you have a lawyer and a domain name. The lawyer should be helping you with steps such as name registration.
I suggest you Google "inventors" and also look at the books available at amazon.com. It's a big topic. There are lots of checklists around.
Start with the thinking. You don't necessarily have to do a full business plan, but give yourself a break and think it through, whether or not you actually prepare a full, formal document. Write it all down for yourself first.
Good luck with it,