Since you already got the DQ email, your case will now be queued for interview and you can safely ignore that message for the NVC stage. That's just a generic message sent by NVC to those with taxed income less than the minimum required for sponsorship, regardless of their actual financial capability. Key point here is that the "consular officer will decide if you meet these requirements at the time of the interview."
As for the visa interview in Manila, evidence of current income is really more important than past income. If your current income is well above the minimum required, no need for a joint sponsor. Maybe a week before your wife's interview, upload a more recent pay stub to CEAC. If you can get a more recently-dated letter from your employer guaranteeing continuation of your job in the US, that would be good too. Make sure the employer letter is also uploaded to CEAC.