If you just pulled the default version of qwen3.5 from ollama's repo you downloaded a mediocre one that only uses ~6GB.

Check ollama show qwen3.5 and see if you get something like this in the result:

  Model
    architecture        qwen35    
    parameters          9.7B      
    context length      262144    
    embedding length    4096      
    quantization        Q4_K_M 

This is the default version I got when I first tried using ollama without any experience. It worked, but it's a heavily quantized, lower parameter version of the model -- i.e. it's pretty dumb -- compared to what you can actually run on your hardware.