Hi, another 2b-er here. I can only echo what the others have said, 2b hair is wildly unpredictable and somehow we've got to find a way of accepting that. I'm MUCH older than you and I'm still struggling with it, so I do sympathise!
I think we are often our worst critics too, I've recently had two different guys genuinely not understand when I complained about my hair and say, 'you're crazy, your hair is great, it's just part of you.' So I try to think of that when I look in the mirror.
And believe me your hair looks better behaved than mine - mine is very, very fine, very, very fluffy and a mad mix of wavy bits, curly bits and straight bits.
I tried CG techniques and tons of products on and off for 3 years and my hair looked worse at the end than when I started - so don't be too disheartened if you can't buy loads of products, I think with 2 hair it's more about routine, and you can still try out all the tips and tricks on here. Some will work, some won't, try not to get too disheartened over those.
Each time I ditched CG in despair I found I kept stuff I had learned which did work.
For what it's worth, I now shampoo with a gentle sulphate shampoo and use either a conditioner with a silicone or Moroccan Oil, which also has silicones.
I detangle wet hair with a Denman, comb with a fine tooth comb to smooth the fluff, scrunch with a microfibre towel, comb through again with the Denman to clump the curl and then lightly blow dry - a diffuser just creates a horrible mess (and I should know, I bought three of them, convinced one would work!)
All of that is really against the 'rules' of CG - but it works well for me and I would never have found it without trying, and failing, at CG.
The other thing that helps me hugely is a silk pillowcase - my hair usually (but not always!) looks good for a second day if I've slept on that. Before I could afford one I scrounged a scarf in a silky material from my mother and slept with that thrown over the pillow.
I'm not saying any of that will necessarily help you, just that some of what you find on this website certainly will, so hang in there!