I understand it is a tough wait (I am just as impatient), but like @OldUser said, it is normal. Some people get interviews scheduled 2 weeks after applying, for others it takes 9 months or more...and while which field office you are with does play a role, it is still not FIFO. People who filed after you at the same field office may have interview and oath before you. While "clean cases" probably do get processed faster, the largest factor is just plain luck (probably based on which officer your case is assigned to and their case load.
You can look at May, April filer threads, plenty of people there who are still waiting for interview, and they have clean cases too. So I wouldn't think anything is wrong. I would reserve the congressional enquiry route for a 9 month mark. For now, as hard as it is, you just really can wait.
Also I know that NYC is REALLY slow, like 9+ months is normal there. I don't know about Newark, but being so close to NYC, and with such high population of immigrants, I would imagine it can't be much faster than NYC. So there is that additional factor for you.