Sorry, but an attorney really can't answer your question without knowing all the facts of your case & all related and detailed information regarding your reason for attempting to withdraw your plea. You need to speak to a local WA criminal attorney to review this matter - many will not charge for a consultation. Also, if they decide to represent you they might consider a payment arrangement if you can't afford the full fee.
This is not intended to be legal advise or as legal representation. I am a California personal injury attorney . Be aware that every state has its own statute of limitations; and statutes & case laws that govern the handling of these matters.
In the State of Washington a plea of guilty must be made in a knowing, voluntary, and intelligent manner. The analysis of whether a plea was made in such a manner becomes much more complex beyond stating the general rule. You should talk to a good criminal defense attorney about pulling the change of plea paperwork and the recording of the plea hearing to see if the plea satisfies the requirements in question. Generally speaking,it is an uphill battle.
You can argue any relevent reason to withdraw a plea of guilty but understand that it is very hard to accomplish. You need an attorney