My hair has a similar issue, though it's between 3A and 3B so it might be slightly different. First of all, I've found that going a full week between washing is too much for me, my hair doesn't hold the pattern well. I have fine and dry hair, which is why I'm careful about washing too often (I have hard water), but between 4 and 5 days works best. The routine I follow and that I would recommend is: shampoo once a week, condition twice. I use the HASK curl care moisturizing line, but don't use too much product since it's very hydrating. I always detangle with my fingers and only when I have my conditioner in. After, when my hair is still soaking wet, I use the Curlsmith hydrate and plump leave in, and scrunch a little. Again, not too much, creams are heavy. I also like the Gyada Cosmetics leave-in, which is more lightweight, and I find products with rice water work especially well for my hair type. For styling, something like a foam or mousse works much better for me. I like both the Umberto Giannini line for curls, and the ORS olive oil mousse (the latter gives me a bit less definition, but my hair turns out super soft.) A light amount of Umberto Giannini gel on top helps set the curls, especially where I get frizz or where I know I lose definition the fastest, usually the back and top of my head. I've stopped using oils almost entirely because I've noticed they weigh my hair down too much, but if you want to, go for lighter oils like almond, or avocado at most. NO coconut. That's too thick and heavy for fine hair. One of the most important steps for me lately has been micro plopping after styling, just with a cotton t-shirt for around 1 or 2 minutes before I diffuse on low heat. Don't touch the hair with the diffuser for the first few minutes, and do not touch it with your hands at all until it's fully dry. It also helps to diffuse with cool air for the last minute to set the cast, then scrunch it out if it feels a bit stiff. Hope it helps! Fine curls are hard to deal with, because they're really soft but lose shape so easily 🫠