I have tried numerous moisturizers - cosrx snail mucin, Glow recipe , Vichy mineral 89, clinique 72 hour moisture surge , kielhs. When I compare my skin without a moisturizer, I find myself getting oily near T-zone after 3-4 hours whereas with a moisturizer i turn oily in 1.5-2 hours!! what am I doing incorrectly!!!

I would suggest, instead of a moisturizer, a serum that contains a high concentration of hyaluronic acid and/or ceramides. Some great options are The Ordinary Hyaluronic Acid 2% + B5 or the CeraVe Hydrating Hyaluronic Acid Serum.