Amazing hydrating serum or oil?
Do you normally have super dry skin or was it just for the winter? If your skin gets dryer in the winter, remember to drink more water and also use a humidifier, it really helps your skin. I start the day with 2 cups of water, then go about my day, and I sleep with a humidifer on the night stand. There is a noticeable difference in my skin when I don't do those things.
Do you put a moisturizer on top of the serum or oil? what moisturizer are you using? serum/oil might hydrate your skin, but if you don't put a moisturizer on top, especially for dry skin, it's still dry (kind of like how you can sprinkle water on bread, but if you don't put saran wrap on top, the bread still dries out). The only oil I see you haven't tried is Dr. Dennis Gross Vitamin D. First Aid Beauty skincare line is targeted toward dry skin. I have heard some people swear by coconut oil or grapeseed oil on the face (both can be found in most grocery stores). I'm assuming you are using a nice heavy/protective moisturizer on top of the serum. Are you using a toner? if yes is it a hydrating toner?
Have you tried an enzyme mask or hydrating mask? Your skin slows down during the winter so it takes longer to recover, and an enzyme mask (Ren F10's really good) help to jumpstart it and some have acid/peel to help slough off the top layer so whatever treatment you use sinks deeper into the skin and is more effective. Hydrating masks are exactly what they sounds like, and some can/meant to be left on overnight for better results. I haven't tried any hydrating mask since I have combo skin, but when my skin is desperately dry, I make a scrub from brown sugar+olive oil+honey, scrub then lightly rinse off. It feels like there's an oily film on the face but if my skin truly need the moisture as I believe, it will sink in after a couple minutes and I can do whatever.
Try Philosophy's When Hope is Not Enough Omega 3, 6, 9, Replenishing Oil.
It's a dry oil so it feels very light and after you work it in, it almost evaporates into skin.
My cousin who got dry patches from harsh acne medication loved this oil. It's on the Philosophy website and still sold in Ulta. I'm not sure if it's still available in the kit with their complimentary moisturizer, but they have the serum separate too.
In additional to healthy omega fatty acids, it has sweet almond oil, sunflower, sesame, corn, macadamia, olive, and lineseed oil, plus vitamin A (retinyl palmitate) and rice enzymes.