Law / US Citizen has somewhat complicated travel problem. [6]

Here is the situation. I came to Poland with a visa-free regime from the United States. I then went and volunteered in Ukraine after staying about 2 weeks. I made multiple trips back to Poland in this time WITHOUT ever going over my 90 Day Schengen law. Before this time ran out, I was hired by a Polish company who did all the paperwork for a Karta Pobytu.

All documents were done and sent to the Immigration office. This paperwork is still being processed by the government. I would like to return back to the United States and if possible cancel this Karta Pobytu, WITH the hope of returning to Poland after staying in the United States for 90 days, as stated by the Schengen law. I do not want to be banned from re-entering the EU! Is this situation normal?

Could I simply go on a plane stay 90 days in the US and return under the 90 day Schengen agreement? Would I be banned from Poland after this huge mess? If more details are needed I'm happy to provide. Thank you.