First, the fact that you are under stress and taking medication for it is not a defense to a criminal conviction, unless you can show that the medication was so strong that it effectively meant that you literally did not know what you were doing.
Second, four years is not "so long ago" when you are talking about two felony convictions, so that will nothelp.
Third, you cannot get the first conviction expunged. The only time you can get a something expunged is when you didn't do it in the first place, or you have received a full pardon for it, or the conviction has been reversed on appeal. Since you say you were convicted, that suggestssthat none of those circumstances apply.
Finally, questions about the penalty you are likely to face for a criminal offense are very fact specific. Sentences depend on things like your prior criminal history, whether you are charged with one offense or multiple offenses, whether state law allows or requires the sentences to be run consecutively, and the particular circumstances of your offense. It also depends on what is typically done in the particular court you are in, that is, whether the judge who is sentencing you tends to sentence heavy or light, what kind of plea agreements the prosecutor is willing to consider, etc.
However, I am not an attorney licensed to practice law in your state, and this is not legal advice. For that reason, and because cases like this are very fact specific, I would recommend that you contact the local bar association’s lawyer referral service (they all have them) to locate a lawyer who practices OR criminal law. Moreover, there may be nuances in state or local laws or customs and practices that affect your situation and that only an attorney in your state would be aware of.
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