Who should I trust to tell me if my settlement is fair?
You certainly do not want to rely on anyone from the insurance company, including the insurance adjuster and your insurance agent. Their job is to minimize your claim. They will not want to pay you a large amount of money because they are working for the insurance company, not you. Your doctor is probably someone that you can trust to properly treat you for your injuries, but he has no idea of what your car wreck claim is worth.
You need to find an experienced personal injury lawyer to help you with your case. You should do your homework and make sure that the lawyer that you select handles the type of case that you have, will handle your case personally, and will try your case if it goes to court. The lawyer should be able to answer your questions and make you feel comfortable that your claim will be properly presented to the insurance company.