Adjustment of Status - I-485

Hello y'all, here I come again, I'll try keeping it short and sweet and hopefully find someone who's going through the same experience

I've been happily married for a bit more than 2 years now to my US Born wife, we have 2 beautiful daughters together (I'm a stepdad to her first born) and we have a third one on the way <3

Now, we got married back in October 2016, and I waited until May 2017 to start my process (I-485//I-130). Shortly thereafter I did Biometrics, and then in August 2017 I received my EAD (I'm still waiting to get my renewed AED). And I work as an EMT in South Florida while I wait to finish my Paramedic School.

Anyways, after many months of waiting, I've tried Infopass, Phone calls, Online help, Tier 2 "representatives"... But nothing else is happening. For months, my status updates @ USCIS webpage for my i485 just showed a message saying "We cannot provide any information at this time", and then not too long ago, it finally started displaying a message saying my case is ready to be scheduled for an interview as of March 2018....

(note that my case started well over 17 months ago now)

What am I doing wrong? I've seen cases of people who go in and out, or started their process after me and are already done : /

My field office is Oakland Park, FL. And I need to know what's going on, is this normal? or should I be concerned?? This is putting a huge hold on my carreer due to the fact that I aspire to serve as a Medic in the Military, but clock's ticking!!!

I appreciate all the feedback you can provide as usual, and wish y'all the best.

Rick