I suspect we are teachers on different continents, but I think our experiences are probably more alike than different. I would challenge you to consider why you want to teach. Only you can answer that question, and the answer will dictate what you should do.
Some years ago, a wise person told me that some teachers teach because they need the affirmation of the students, that that affirmation feeds a teacher's ego. Then this sage told us that some teachers teach because it is a mission, sometimes a mission without lots of affirmation because the kinds of kids they teach aren't in a place emotionally to reward teachers in that way.
I am not sure that person was wholly correct, but her comments made me rethink why I keep teaching. It's not about me; it's about the kids and what I can share with them that will keep doors open for them.
On that note, I, too, am an English instructor. It is hard to cover all the subjects under the umbrella of English well. It is also hard to meet the demands of mandated standards.
If you answered the essential question regarding why you want to teach with some sort of "I want to make a difference" statement, and you combine that with the feedback you have received in your previous experiences, I think you need to contine your program.
The earlier stages of teaching are grueling. You are learning more than the students and on many more levels. You have to master classroom management, find a way to deliver content so it makes sense to a variety of learners, navigate the "colleague " relationships, which can be daunting on occasion, and find time to renew yourself physically and emotionally. If you are married and/or have children this is even more challenging.
Our world needs good teachers who can remind themselves that what they do is critical to the survival of society. Our job will become ever more challenging as we face more distractions, more government interference, more emotionally needy students. If you find even a bit of passion for your subject or your students, I hope you persist in your career. Who knows who you will influence and in what manner.
All the best in a difficult but delightful field. I have taught for 27 years and find myself questioning the same things you do. Fortunately, I have a few of those moments that make me realize why I teach to renew my soul when things seem so bleak.