Contributing to traditional IRA after filing

I know I cannot deduct contributions because of my income.  I intend on converting the traditional IRA to a Roth IRA in a backdoor conversion.

 

I've already filed my taxes for 2022.  Can I contribute the 6,000 yearly max for 2022 even though I filed already?  Would I have to amend?  I realize I'm cutting it down to the wire here, appreciate the help!  Was just reading about backdoor Roth and it seems worth it to contribute to a traditional IRA to covert it.  I'd like to take advantage of this for 2022 but unsure if I'd need to amend or not.