There's a small ray of sunshine for you, if all your sales were covered the IRS knows if you owed on a tax return and would have let you know by now if you did.
So if you compute your taxes and you won't owe anything for any of those back years then just keep your records and don't bother filing. Although if you have losses that you could have carried forward to negate the gains that you have this year then it might be worth your while to file the older years. But if you compute the 2020 taxes and you still owe nothing then why bother. This is a judgment call you have to make.
