The statute of limitations for Oklahoma is 2 years according to various web sites. I just checked at
https://law.freeadvice.com/resources/personal_injury_statute_of_limitations.htm
That means you don't have much time to pursue a claim if your accident was 1-1/2 years ago. I would consult an personal injury attorney (one who offers a FREE initial consultation) and, if hired by you, get them to file first an extension to the statute of limitations for *your* claim and then file your complaint.
P.I. attorneys generally take between 30 - 40 percent as their "fee" but you will sign a contract when you decide to hire one. Make sure you understand what you are signing and how much you will pay from your settlement. so it won't be a surprise. You must decide if it is worth it to hire an attorney , and for cases with serious injury or cases where the statute of limitations may run out, you probably should at least go see a few lawyers (that offer FREE consultation lol) and find the best one for you!
Good luck!
~Diane~