Recap:
your fan is efficient enough. definitely use a carbon filter whether youre medical or not.
If you have a cop neighbor, just dont have people over, and make sure you keep your filter fresh.
As someone mentioned earlier, keep your grow a secret. GF's are the worst thing for your freedom.
in addition to using a carbon filter, try to keep your grow room pressure negative so the smell doesnt seep out.

hope this helps.