I hate fucking taxes. Just stayed on a call with Fidelity because I overpaid my 401k by a few dollars and they don't know how to set a reimbursement. Now I'm on a call with Anthem because they don't know why I never got my 1099-SA. Fuck. I really fucking hate taxes.
Just file for an extension, it'll give you until October (?) to complete your taxes with the proper paperwork.
Few years ago, I estimated my pay/taxes because a former employer never mailed me my W2 since they just sucked. I'm foggy on all of the specifics, but I remember getting a letter saying they couldn't verify the info from that W2, and that I wouldn't get my refund until it was verified.
Got the company to send me my actual W2, filed a revised return, and ended up owning like $1700, even though it had told me before the letter I'd get a refund of like $3k. Annoying as fuck, but ultimately my fault, I should've just waited for the W2 and filed for an extension in the meantime.
Following year, I got a letter from the IRS saying they owed me $1300 that was never released due to my tax shenanigans the previous year.
Moral of the story: just file for the extension, save yourself the anxiety and headache.