I feel like my hair hasn't been rinsed properly.
This can happen sometimes. When your hair is used to chemical products, it tends to "suck up" the chemicals. Because it's not used to natural hair products, it takes a while to adjust and goes through a sort of "detox" process. This explains why it might seem like your hair is badly rinsed. When you switch to a natural shampoo, you have to get through this difficult detox period, but it's worth it in the end! In the meantime, you could always rinse your hair with a vinegar and water solution, or use an apple cider vinegar rinse to solve the problem until it goes away naturally – which it will!