How do I determine if I have met the requirements for an Overseas Service Ribbon?

I concur with MSG (Join to see) that you are not eligible for credit for completion of the overseas tour, so not eligible for award of the OSR.
600-8-2 5-4 a. ....It is awarded to Servicemembers of the U.S. Army for successful completion of overseas tours...
b. .... Soldiers must be credited with a normal overseas tour completion in accordance with AR 614–30.
AR 614-30, Table 3–1
Eligibility for overseas service criteria (reassignment).
Rule--33.
If a Soldier--Applies for officer candidate school or warrant officer appointment before being alerted for overseas duty.
Then the Soldier is—Ineligible
Unless—Soldier waives the commitment in
writing.
NOTE: I don't believe rule 35 applies to WOCS.
Rule--35
If a Soldier--Is selected to attend an Army Service school or a senior academy preparatory school.
And—Alerted for overseas duty after approval for school
Then the Soldier is—Ineligible
Unless—Soldier completes or is removed from the course, or can complete an overseas tour prior to the course start date.

When did you submit your packet for WOCS? I ask because in AR 614-30 Table 3-1, Rule # 33: Applies for officer candidate school or warrant officer appointment before being alerted for overseas duty then you are ineligible.

SPC,
I do not believe you were in country for even a short tour, be it long and short tours there are requirements to follow. Ask your personnel PSNCO, but I am sure I am right.