I'm retired but received a check & 2018 W2 from my previous employer for profit sharing that was attributed to 2017. Can my wife and I each contribute to an IRA for 2018?

I have no other employment income. I am no longer allowed to contribute to my 401k since I am no longer employed. Can my wife and I each contribute to an IRA for 2018 since I received a W2? Is there a disadvantage to this? I converted some funds from a previous IRA to a ROTH in 2018; does this affect my eligibility to contribute again? Thank you.