To clear something up...you can have an LLC, AND have a DBA. A LLC is a legal entity, a DBA is not. There are a few different types of legal entities: Sole Proprietor (which is probably most commonly associated with DBA), Partnership, LLC, and Corporation (S-Corp and C-Corp). Sole Proprietor and Partnership provide no legal protection whatsoever. If someone sues you, they can take all of your personal possessions. In a LLC or Corporation, if you are sued, they can only take what the business owns.
A DBA is a fancy way of saying "My business name is ....". If you do an LLC, the official name MUST have LLC in the name. For example, the company may be named "Jon's Tire Shop, LLC". So, Jon gets a DBA of "Jon's Tire Shop". Later on, Jon opens up a new website called "TheBestTiresEver.com". In order to legally use that name to accept payments under it, Jon would need to get another DBA for "TheBestTiresEver.com", OR accept payments as "Jon's Tire Shop". Legal entities can have multiple DBA's. In fact, my company has something like 9.
Yes, you are a little behind the ball regarding taxes. Everything you did will be situated as normal income. Assuming you documented all of your expenses, you still can write off your expenses.
Disclaimer - I'm not a tax professional, and I am not giving legal advice. These are simply my opinions based on my experience.