You might be able to have the Felony removed from your record. First, it is helpful to know what the Class of Felony was (Class A, B, or C). The clock starts from the point when you completed all the conditions required by the court and obtained a Certificate of Discharge. For more information view the links below.
Whether you can expunge/vacate this conviction depends upon whether it was a Theft First Degree or Theft Second Degree. Theft First Degree is a Class B felony, which requires spending 10 years crime free in the community after completing your sentence and probation. In that case, you are four years shy of being eligible for an expungement of this conviction.
If it was a Theft Second Degree, you would be eligible because that offense is a Class C felony which requires only five crime free years in the community for eligibility.
As to whether you need an attorney; you have a right under the Constitution to represent yourself in court. However, there is a very old, very true saying about people who do this. "A person who acts as their own attorney has a fool for a client".
The state of Washington allows the court to vacate certain non-violent convictions and to seal the record. Once vacated (expunged), the person’s criminal record will not include that case. State law gives you the right to state to anyone, including prospective employers, that you were NOT convicted of that offense, after a vacate motion has been granted.
To be eligible you must complete your sentence, been discharged from court supervision (probation/parole), not have any charges pending, and be conviction free for the waiting periods listed below. The waiting periods begin the day you complete your sentence, including probation/parole.
Class B Felony 10 Years (Felonies before 7/1/1984 are not eligible)
Class C Felony 5 Years (Felonies before 7/1/1984 are not eligible)
There are attorneys who specialize in this process. They seem to charge around $850 to $2500.