Just a PSA for any that might find it useful: Talk to the IRS if you have any issues like this (not filing, under-withholding, etc.)! I know someone that had thousands of dollars in fees waived by simply writing a letter (like 3 sentences). Basically got a response that said "All these fees are waived. Just don't do it again."
I know I'm just a random internet stranger, but I'm proud of you for sending that email. I say this as someone who has experienced similar magic in the past, but more significantly, am currently bogged down with many similar problems that are quite solvable in practice. Taking that first step when you're so overwhelmed you just want to hide from everything is hard