Many factors such as age, prosecutor discretion, what judge you have, whether witnesses are credible all matter and that makes it near impossible to say what type of time you'll do if this is second degree forgery.
You can miss defenses and say the wrong things if you are not represented by an advocate as your attorney.
You might find my Legal Guide helpful "Ethics: Yes I Need a Lawyer!"
You might find my Legal Guide helpful "How to Choose A Lawyer For You."
You might read my Legal Guide "Can An Attorney Really Help?"
You might find my Legal Guide helpful " What Do I Tell My Lawyer?"
Online we cannot know what the other details are going on in your case because online we cannot find out those details. You need a lawyer. Check with a lawyer in your locale to discuss more of the details.
Good luck to you.
NOTE: This observation is made available by the out-of-state lawyer for educational purposes only and is not like communication with a lawyer with whom you have an attorney client relationship along with all the privileges that relationship provides There is no attorney client privilege between you and the attorney responding.
You have a reasonable chance to work out something that doesn't include prison time, but you really need to hire an attorney to help you with this. Attorneys negotiate with prosecutors every day and know what they are looking for to persuade them (or a judge) not to give you time.
It sounds like you are referring to possession of counterfiet currency, so it is unusual that you would be charged with a state offense rather than a federal offense. Are you sure that you don't also have pending federal charges? Even if you were not the owner of the vehicle, if you are the only person present in the vehicle and there is no evidence of recent possession of the currency by someone else, the state can argue that you were in actual or constructive possession of the bills. Forgery is a felony punishable by one to ten years in prison. For a first felony, prison seems unlikely for you. The three months you have already served should be enough. But a probationary sentence of three to five years will likely be your sentence, depending on the jurisdiction where your case is pending. Please consider hiring a lawyer to defend you.