Do a search on "settlement" or "claim" or variations thereof on this web site. You will find lots of info or speculations of settlement amounts. It varies very much by the state and county that you live in. The same injuries in one state might bring $5,000 and in another $20,000. It depends on many factors. Whether this is your first car accident, first-time injuries, whether you go to a chiropractor or a physical therapist, and of course whether you have an attorney or not, etc.
An attorney *may* get you more money because of his/her negotiation skill, but then you will have to pay his/her fee. So you should weigh that factor in also. If you are a good negotiator yourself and the money and injuries involved isn't that great, you should try to settle first yourself, I believe. You only have $4,500 in medical you said -- that isn't a great amount. You may get 1.5 to 4 times that amount as a settlement. You might get more. They will probably offer you less at first. I have posted many times on my own settlement experiences.
This site (as well as others found through a web search engine) has a wealth of information that is veryhelpful in "guesstimating" a settlement amount that you can live with. And *if* you and the other side cannot come to a mutual agreement, then you have to file a lawsuit. I think you should always keep that option open, as you will not appear desperate to settle and you might possibly get closer to what is a fair amount.