For most of us, dewpoints in the 40/50s would be considered ideal, LOL! I live outside of Philly and the dewpoints were mid70s for a few weeks; however, they can fall into single digits in the winter. Your thoughts are on the right track. You do want to moisturize more and do something to retain it. You should be using more moisturizing products in every step.

Many of us rotate products. I wet, use a rinse out and style every day. Seldom let myself use any one product more then once in five days, if that. Looks like you're using the same product for almost everything--TN Raidiant Volume. Not sure adding castor oil to it would be considered a DT. Maybe you need to buy a product that's supposed to be a DT and start from that. In the winter, when we have low dewpoints, I do use a minute amount of a DT as my leave in (I have low porosity hair and have to be careful.)

Many folks on use the "Yes To" products with great success. If you need to do drugstore type products, some of them might be good choices for you.
3a (Corkicelli), highlighted, fine, low porosity

HGs: Anything Sevi; Curly Kinks Satin Roots, Curlycue ReNew and Coil Jam; homemade FSG and okra gel; soap bars; UFD Curly Magic; Botanical Spirits Jellies, CJ Repair Me, Aloe Fix