I am very experienced in defending students in academic integrity cases, both in negotiating these matters and in defense in administrative hearings (usually more closely resembling meetings). But it is difficult for me to determine from your post what legal issues and options may yet remain here.
You have utilized the available admin process. It's not unusual or significant that your attorney was not permitted to participate in the hearing. That is typical. But you were allowed legal advice and assistance in developing your defense. That is all that due process requires in these circumstances.
It is also not unusual that you lost on the merits. These are always very difficult cases and students are seldom vindicated. The process is not a level playing field. A faculty member made the accusation. The charges were heard by school officials, and the matter was decided by standards and rules adopted by the school. These cases always involve trying to persuade the school that the school is in error. Hard to conjure a more difficult or unlikely persuasion mission.
In most of these cases, the result is damaging because of the affects and consequences of the result. Often the best strategy is to trade off defense and proof in favor of negotiating an agreement for confidentiality of the results, even stipulated results, or a stipulation not to resolve the accusation. A sealed record is often the ultimate victory in these kinds of disputes.
But you have already been through the admin fact-finding process, lost on the merits, and now have no negotiating power for trading the burden and risks (for the school) of a defense in exchange for sealing.
Let's be candid, getting into law school with a violation of academic integrity on your record is going to be a steep uphill battle. I don't have any advice about how to sell or package that situation.
Very likely your attorney has already advised re your rights for judicial review of the school admin process and result. Think twice before you elect that option. It is expensive and time-consuming, and the matter will then be in the public record (not protected by FERPA). More critically, courts review only for the school's compliance with its admin process and to test whether there is evidence to support the admin finding. Great deference is often shown by the courts for the school's conclusions, as a matter of fact if not law. Perhaps your attorney can negotiate a trade-off of your court challenge for a stipulation re sealing.
You may have considered a civil action but it is rarely a good option. Breach of contract claims are ordinarily tenuous based on the explicit language in the student-school contract (enrollment and admission materials, school rules, etc.). And tort actions are flawed because the school does not owe you a duty to abstain from disciplining on these charges, or from making such accusation. If the school provided your due process, you very likely have no legal case that can be expected to be successful. There are attorneys who will tell you differently (even here on this Q and A Board). Ask them to identify a similar case with an acceptable result. And ask if they feel strongly enough about that advice to take your matter on contingency. There's the test.
Finally, there is no statutory or admin law basis for "expungement" unless your school offers one in its rules and regs. That would be unusual. I track the disciplinary processes at more than 3000 schools across the U.S. and I have not seen one that provided for expungement.
I know you are stung and offended and feel abused. But if you graduated notwithstanding this event, or can, then the real disability of this situation for you is the record -- not what your undergrad school believes or found. Make getting that record sealed your objective and discuss strategy with your counsel with that narrow focus and goal. If the record is sealed and confidential, you can live with whatever it says.
My responses to questions on Avvo are never intended as legal advice and must not be relied upon as legal advice. I give legal advice only in the course of an attorney-client relationship. Exchange of information through Avvo's Questions forum does not establish an attorney-client relationship with me. That relationship is established only by individual consultation and execution of a written agreement for legal services.