Citizenship

I need an advise on what my next step should be :( Thanks to everyone in advance for contributing to this post.

I had my interview on November 6, 2018 at the west palm beach field office and got a “decision cannot be made” due to my long travel history. However, none of my trips were longer than 6 months and I had maintained my continuous residency throughout. The officer said that she would have to review my application to see if everything seems right and would need an approval from her supervisor due to which she cannot approve my application at this point in time. She said I would be receiving a letter in mail soon. It has been 154 days today and I did not hear a word from them regarding their decision.

I had called the USCIS customer service line multiple times and they asked me to wait till I complete 120 days. After completion of 120 days, I called again and the officer put a service request to the west palm beach field office. I received a letter saying “we are still reviewing your application, and you will receive a notice as soon as we make a decision”. I called the USCIS customer service line again after one week and they just told me to wait and said that scheduling an infopass would not make any difference since the infopass session would provide me with the same information as they did over the phone. I don’t know what to do at this point in time. My sisters and mother who applied with me had the same travel history and were approved the same day. But whenever I state this, I get to hear that everything is done on an individual basis, which I completely understand. But why is it taking so long to make a decision? My application is pretty straightforward. Please share your experience if it is similar and advise if I should still schedule an infopass or not. Thank you :)