Your job sounds uncannily like the place I just left. Right down to the insanely high turnover.
After working in a similar practice for about 9 months, my biggest takeaway was that I went into it without asking the right questions and meeting the right people. Of course, that being said, there were also a lot of surprises that I couldn't have anticipated. A lot of the challenges I faced were similar to yours - overbooking, no admin time, unavailable physician collaborators despite being told they would always be available, not knowing my numbers or what was expected of me, problematic MA's, and always overtime. While I was contracted for 40 hours a week, it wasn't unusual for me to do 50 or even 60 hours a week with the time that I ended up putting in after work and on the weekends.
Working at FQHC's has it's pros and cons as I'm sure you're aware. I LOVED my patients. I loved them so hardcore and still think about them. I loved the difference I was making in their lives and even though the hours were grueling, I found my job to be very rewarding. Up to a point. I learned a ton and, in some respect, enjoyed the complexity. But you DO have to focus on only 1 or 2 issues per visit and that can be very difficult as people are often lost to follow up for months or years at a time.
As time passed I did become faster and more efficient when it came to seeing patients, labs, returning phone calls, paperwork, meds etc. But as that happened, I also became more and more miserable in my personal life as my work-life balance really suffered.
Of course your situation is your own, so I can't advise you one way or the other. It could be newbie blues, or it could be a toxic environment. Only you can decide if your environment is something you need to warm to or something that is just increasingly making you miserable. Have you tried speaking with your collaborating MD? What does your friend have to say about your experiences?
Whatever you decide, I wish you the best.