While it is good to get going finding a lawyer and preserving evidence, you don't want to settle too early with the driver's insurance company. This accident just happened and quite often there can be additional injuries that are not apparent right away but show up a few weeks or more later. You want to have a good idea of the full extent of injury before settling with the insurance company. Your lawyer will advise you on that. And, it should go without saying but I'll say it anyway, get and keep copies of all the medical bills and related expenses that you get as a result of this injury. You don't want to leave something out of your claim.
The way things appear now does not indicate the level of long term damage done. There are different degrees of TBI. A person can have a concussion but not experience long term or short term damage. If the ER doctor did not keep you overnight for observation. That is a good indicator your injuries are not as serious as you think they are..
It seems like you think you are going to get quite a bit of money from the insurance company. I am just saying you need to be prepared and be realistic. Have you seen your primary care doctor for a followup? When do you plan on returning to work? Did the ER doctor give you a excuse for work?