I had a similar situation coming home from my 2/c cruise. My seabag made it back, but about 1/3 of the items inside did not. Boots, belts, one white shoe (who takes one shoe?) were missing. I called American Airlines, and they had me fill out a reimbursement form with the approximate value of the items. I got the full value I asked for, and bought new items once I had the money.
Keep trying the airlines, and make it clear that you are a military member traveling on official orders (summer cruise orders count). And contact your unit, they should be able to get you new uniforms before school starts.