Another option is to ask in Naruto - related social media groups. There are groups on platforms like Facebook or Reddit where fans discuss all things Naruto. If you post a request for 'Obito x Naruto fem fanfic', someone might be able to point you in the right direction or even share their own favorite ones.
You can try looking on fanfiction websites like FanFiction.net or Archive of Our Own (AO3). They usually have a wide variety of fanfics, and you might be able to find some great 'Obito x Naruto fem fanfic' there.