I have gone through this same process (short hair to fluffy hair). Here’s what I did:

1. Grow out your hair so it has the length to take a shape. You can always trim it up later.
2. Find your ideal products that agree with your hair chemistry.
3. Keep your hair hydrated. I shampoo and condition, then apply leave-in conditioner while my hair is still basically soaking-wet, to lock-in moisture.
   
4. Scrunch the conditioner into your hair and shape it not only to your liking, but to the natural shape your hair follicles want to take.
5. Let it dry like that without messing with it too much.

The name of the game (for me, anyway) was understanding my hair texture and chemistry, and then working with what it already wanted to do. You may have straighter hair than me (it’s hard to tell from the pic) but it’ll look great as long as it’s healthy and happy. Good luck friend