So I got pretty caught up in the protein thing and completely forgot about gel.
For me, gel is also very important in keeping frizz at bay. I use about a quarter-size of BRHG in my just-past-shoulder-length hair basically every day. I haven't found a gel my hair does better with. It has a really hard hold which helps preserve my curls while they dry, but then I can easily SOTC. May just be something to keep in mind, if you want to try different gels. If I don't use gel, my hair can be pretty poofy and frizzy. But, my curl pattern is 2c, so less tight than yours.
Another thought - have you tried sealing with oil? That can help with frizz.
Just another couple ideas for you, hth. I wash and style in the morning even though drying time is fairly long (a few hours) so I'm not much help with advice on preserving curls overnight.