Yes, documents due on Sat or Sun or Federal holidays are timely if filed at the USPTO on Monday, and that includes TTAB Cancellation. You are right, you are in way over your head. If you are failing to disclose or produce and making the other side file motions to compel, the judge will have ill-will toward you, and rightly so. The judges do not like pro se litigants because they make the Judge do a lot more work so some, usually foolish, pro se litigant can save attorney fees. Get a lawyer and quit doing this yourself. Sounds like you are losing badly.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.
There are general attorneys who cannot even navigate their way through TTAB proceedings so if you are not an attorney at all, forget it. Either hire a trademark attorney or just surrender the registration & really save yourself money.
Alex Butterman is a trademark attorney with Staas & Halsey LLP (http://www.staasandhalsey.com), a Washington, D.C. IP boutique law firm. Alex is admitted to the bars of Washington, D.C., New York and New Jersey but, unless otherwise specified, the answer is intended to be general enough to apply to any U.S. state and based primarily upon his knowledge and experience with applicable federal laws. The opinions expressed are those of the author and do not necessarily reflect the views of his firm, Avvo or other attorneys. This answer is for general information purposes only and is not intended to be and should not be taken as legal advice. No attorney-client relationship or obligations are established herein, although consulting an attorney to discuss your specific situation is strongly recommended. This is especially true of trademark law because TM law is so fact-specific and full of esoteric nuances and exceptions that could easily result in a critical legal error without proper advice from experienced trademark counsel.