Since you were able to file for AOS (adjustment of status), I am assuming that you are married to a USC. If married to an LPR, falling out of status after filing is OK as long as you were in a lawful status at time of filing. As the spouse of a USC, you are only required to make a lawful entry, falling out of status, even before filing is OK (with the rare exception of someone who came on a visa waiver and then they have to file within 90 days of entry).
According to your post, you ARE now an approved immigrant (probably a conditional rsident if the marriage was ubder 2 yrs at time of approval). As such you are no longer an international nonimmigrant student (F-1). No more I-20 required BUT you just have that other non-immigration related issue with the school.
Good luck,