I used poloniex.
Anyone know if poloniex submitted any information?
since Poloniex is based on US already, then it is best if you assume that they have reported your history to the different government agencies. even if they haven't it should always be a possibility that they will do in an instant upon request.
You should take note that not all of their clients' trading history are being submitted to the IRS for review, the order for them was to submit "random" trade reports or unusual amounts of trades coming from their clients. And yes being a U.S. compliant exchanges I expect them to be one of the companies being required to submit trade reports. @OP are you sure that your calculations are done properly? Because the IRS won't even be on your radar if the gap from your real earnings is that big from what you have reported. And you also don't have to worry if you didn't fabricate your tax report as you'll just get a re-audit from them at best.