Hi u/Coliexsunshine, the official IFS directory is always a good resource as it shows people who've completed an official IFS training - https://ifs-institute.com/practitioners. You can filter your search by state and city.

I searched for "Long Island" and found this: https://ifs-institute.com/practitioners?country=All&us_state=NY&city=Long+Island&approved_consultant=All&level=All&availability=All&consultation_availability=All&field_acceptphone_value=All&keyword=&field_geofield_proximity%5Bvalue%5D=100&field_geofield_proximity%5Bsource_configuration%5D%5Borigin_address%5D=

Please note: The IFS directory lists anyone who's done an official IFS training, but not all of them are mental health professionals. Many are coaches or regular lay-people. Check the bios carefully to ensure it's a therapist, if that matters to you.