Frizz can be caused by many different things. A few things I've learned here:
1. It's important to use the right products for your hair type. Knowing that you're a 2c/3a is a description of your curl pattern. Your hair type includes porosity and density or texture. These links can help you:
Live Curly Live Free - Curly Hair Basics
Curly Hair Tips, Styles & Products - NaturallyCurly
2. Frizz can be caused by not having enough moisture in your hair. Your hair may feel dry and brittle. It can also be caused by over-conditioning. Your hair may feel mushy.
3. My hair is fine and prone to build-up. Even products that don't build up on others will find a way to build up on my hair. I need to low-poo regularly and avoid the temptation to try every product I read about on these boards - especially all at once!
4. Touching/manipulating my hair while it's drying will always bring on frizz for me. I need to apply my products to wet hair then sit on my hands until my hair is completely dry.
There are other things that come into play but these are the top ones for me. It takes time, trial and error to hit on the right products and styling techniques that will work best for your individual hair. Hang in there!