Records created by and about military during the course of the war are not the only types of primary sources useful for research on the campaign in Luzon.
Army officers (as well as officers from the other services) while attending military service schools such as the Command and General Staff College (CGSC), the Army War College, etc. as students have long written research papers on operational military history topics just as you are doing now. Many U.S. Army officers attending military service schools during the late 1940s-early 1950s were World War II veterans and sometimes when writing on a World War II topic were able to draw on personal experience. This means that some of those papers contain primary source evidence. Not all do, of course, and therefore one must scrutinize carefully the nature and evidence employed. Yet many of these can be valuable. Student papers from the Command and General Staff College can be found in the Combined Arms Research Library Digital Library. Student papers from former Infantry School and Armor School can be found in the digital collections of the Donovan Research Library at Fort Benning. Note that collections of students papers at each library include those written by World War II veterans *and* papers written by officer students in later decades up to the present day. Some of the latter may be about the liberation of Luzon campaign and might be included in your search. Although those would be secondary sources, they might still be relevant to your research. Selected ones have been included in the materials provided by your instructors on your class Microsoft Teams site, but careful searching may lead to others. Learn to look carefully at all results and judge what might be useful to your own scholarly inquriry.
Many of the men and women who fought in World War II, from private to senior officers, later wrote memoirs of their experiences. Although historians must use such evidence with caution, especially when written many years after the writer experienced the events described, these sources can nevertheless be valuable. You can locate some using the Library's search tool - Scout.