A defendant or their attorney MAY be allowed to present to the grand jury, but you're not entitled to it. In fact, it is a bad idea for the defendant to go before the grand jury, but the attorney can sometimes make a good presentation.
As for the 2 months, have you been offered bond? If so, but you can't afford it, after 90 days in jail without being indicted your attorney can move to have your bond lowered to an amount you can afford. The state has quite a while to prosecute and many times in an intoxication manslaughter case they are going to wait until the blood tests come back to ensure an indictment.
Good luck to you
A Defendant can request to present evidence or testify before a Grand Jury. As one of the other posters stated, it is not an entitlement. Information can only be presented to the grand jury by the defense only as long as the prosecutor is receptive to either allowing the Defendant to testify or presenting a grand jury packet containing various defense exhibits or statements.
A Defendant who chooses to testify before a grand jury is taking on a significant amount of risk. He or she will be testifying in a room of 9-12 grand jurors where there is no Judge, no Defense Lawyer and no rules of evidence. Basically, the Defendant will be testifying under oath with no protections and the Prosecutor and Grand Jurors will have free reign to ask about anything they want to.
Another alternative to actually testifying before a Grand Jury is presenting a "Grand Jury Packet." Many times this is a very effective way to defeat a case at the Grand Jury stage. Grand Jury Packets often contain any combination of letters from the Defense Attorney, character witnesses, additional independent evidence and a statement from the Defendant. Having the Defendant submit a letter rather than testifying in the Grand Jury room is a way to get the story across from the Defendant's point of view, control the information that is relayed to the Grand Jury, and keep the Defendant from being cross-examined without any protection.
The general rule of thumb is that the Prosecutor has 90 days to get a case indicted. This rule really only has teeth if they Defendant is incarcerated. The State cannot hold a Defendant in custody without an indictment for longer than 90 days.
Your post says that the case is 2 months old. That would not be unusual for an Intoxication Manslaughter case where there is a ton of evidence to collect. It is entirely possible they are still waiting on the results of the blood tests, accident reports, photos, an autopsy, etc.
Grand juries are used in some states but not all and also at the federal level. A grand jury proceeding is essentially a tool used by a prosecutor to determine whether there is cause to charge that person with a crime and move forward on the case. Other states including Washington don't use a grand jury system and instead rely on a prosecutor's affidavit of probable cause that includes some preliminary evidence, witness statements, etc. Also, most grand jury systems only allow the prosecutor to present evidence to the grand jury, not the defendant.