First off I want to say there's nothing wrong with having "barely 2a" hair and I don't think the final result looks tangled at all. It's got a little wave-swave and it's nice.
That being said I have a few suggestions:
1. protein. If you have baby fine hair you should probably be getting a regular intake of protein, so look for styling products with protein as well. My hair is on the fine side too (not baby-fine) and nearly all my products have protein. If your hair gets "stiff" then you may have over-proteined, but many fine-haired wavies have said they've never even experienced that. If it's too stiff just follow with a DT or a good RO. In fact, I actually don't need to follow my PTs w/ a DT, and sometimes I don't even need an RO.
Curl Junkie - Natural Hair Care for all types of Curly Hair!: My 2 cents on Protein/Texture/Porosity/Moisture Balance! :-)
2. Try putting in all your styling products on soaking wet hair by scrunching, and then go straight into a plop. Make sure the plop is there long enough to set the waves (at least 5min). Since you're so fine-haired, I imagine even the weight of water would pull down your waves so I think you may need to diffuse. Look into pixie diffusing. I wouldn't air-dry if you want more vavoom. Remember, once the products are in, they're in... don't keep re-scrunching while it's drying because you may actually be breaking the cast.
3. A hard-hold gel is probably a good choice for you. I wouldn't do an LI underneath. Just low-poo, condition (nothing terribly heavy/rich, definitely with protein) and scrunch in the hard hold gel. Remember not to touch it until it dries completely in its cast.
4. Just experiment with other things like mag sulfate. I don't know the difference bw mag sulfate and sea salt so just experiment. Remember these things are drying, but that may actually be a good thing for you since fine-hair can get overconditioned easily. You are right to use a low-poo; I wouldn't recommend cowashing fine and thin hair. I know there is the SM Line that is "thickening" for fine/thin hair (Yucca/Baobab). I don't know if it has more starch in it or what... I haven't used it but am curious about it.
5. Remember that your hair is what it is. To a certain point you can manipulate it and encourage the wave, but if it doesn't want to climb up to a 2b+, love it as it is! 1c-2a is also beautiful! Good luck!