Ooh do I feel your pain! Your hair sounds EXACTLY like mine. When I was little, I had waves and a few ringlets and my hair was very silky, and then suddenly, I hit puberty, and BAM. I have hair that's straight with a few flips, lots of frizz, extraordinarily poofy, and is super rough and unpleasant. I hated it for the longest time, and had no idea what to do. But CG definitely saved me -- it's wonderful! I went from hair that I hated and straightened every day to hair that has big loopy whurls that I'm proud of.
My biggest suggestion -- this is the most important one. Get a REALLY good hair cut. Sure, it might be expensive, but after you get your first good hair cut you can go to cheaper places and just ask them for a trim.
I suggest a Deva Cut since it worked wonders on my hair, but you can go just about anywhere that's good with curly hair. You want some layers to help de-bulk the hair -- but whatever you do, do not let them thin your hair! Thinning and Razoring are awful for curly hair.
The next big thing: moisture!! If your hair really is anything like mine, you need to get LOTS of moisture in it. You can try Co-Washing (replacing your shampoo with a lighter conditioner, like Yes to Carrots) or Low-Pooing (using sulfate-free shampoo, like Renpure Organics) ... which I reaaally suggest. It will help your hair out so much.
Also, if you haven't already, definitely cut silicones out of your hair routine entirely for now. Find a good rinse-out conditioner that is free of 'cones and will moisturize your hair; I suggest Garnier Fructis Sleek N Shine... it's very slippy, very very moisturizing and my hair just drinks it up lol.
You also want to find a good styling products. Most wavies are fans of strong-holding gels. because they help shape our waves and keep them in place. At the moment I like Garnier Fructis Pure Clean, but definitely do some experimenting and see what works for you
Whew, sorry, I talk a lot! But basically -- don't worry, girl. Your hair is beautiful and there IS a way to make that beauty shine! Don't give up on your hair. ♥