I am licensed only in Illinois and Georgia. You should get the opinion of a Maryland lawyer, but the law there is similar concerning these issues.
First of all, make a police report NOW. Better to make one late than not to make one at all. If the police refuse to take a report, I would call the other party and have that person come to the police station so the two of you can make it together.
Secondly, I would make a claim under my own insurance policy and pay a deductible. Get your car fixed and stop horsing around.
If you have no insurance for collision damage, you can file a lawsuit on your own in small claims. Unless you are driving some sort of luxury car, the kind ofo damage you've described is almost certain to be in the small claim range. Bring the witness to court under a subpoena. You are likely to win, and even if you don't, you'll have the satisfaction of having sued the wrongdoer. My bet is that the insurance company for the other party is going to sing a different tune if they have to hire a lawyer to resist your claim in court.
If you were injured, it certainly would be worth contacting an attorney. On the other hand, if there is only property damage (dents to your car, for example), you should probably handle this through your own insurer. If you don't have comprehensive or collision coverage on your vehicle, you may have to bring a claim for the cost of the repairs. Obviously, if that cost is not very high in legal terms (even if it seems high to you), it probably won't be worth hiring an attorney. On the other hand, even if there is only a few thousand dollars worth of damage, I strongly urge citizens to use the small claims court -- at least once. Doing so will empower you to know and understand the process. You will then be able to resolve legal disputes which are expensive but not at the level where you would want to hire an attorney. Small claims court is fast (by lawyers' standards), inexpensive and fairly easy to handle. It is not unlike some of the T.V. shows such as "Judge Judy." You don't need a lawyer and being familiar with the process will give you the confidence you need to resolve disputes in a legal arena that you might otherwise feel you have to ignore.