How Much is reasonable amount for a settlement?

I was a front seat passenger in a one vehicle accident when the driver hit a city street sign. My head hit the windshield..and knocked some of my teeth out and I had some swelling and bruising around my head. Now my family members are telling me that my memory has been comprimised by this incident and I need to see a Neuorologist..at the time of the accident I did not receive any immediate medical treatment.However, a few days later I did receive a CAT scan from my PCP..and was put on pain medication due to this accident., The driver was ticketed a DWI and later was convicted....It has been over a year now..and I have been offered $2000 to settle this...I strongly think this is worth more....what should I consider a fair offer???