Tryin' to make sense of my first year

So, just finished what I can only describe as a hellish first year teaching in a big urban school system. Had twenty second grade students. Loved em all. Didn't succeed in teaching them very much. Couple with severe behavior problems, couple more with mental health issues, another four with substantial learning difficulties. Class was considered a regular classroom, staffed with one regular ed teacher: me. [Support was 5 kids on Edplans who went out 3 times a week for 45 minutes to SpEd room.] Didn't manage to establish much in the way of classroom routines. Spent the year with a lot of noise and movement in the room. Principal canned me. Looking for another teaching job now, want to stay with city system. Feel a little bit like I'm trying to get the number of the bus that hit me; trying to make sense of the year. Figure out what went wrong, what I can do differently next year. Was it me? Was it the kids? Was it bad admin? (Change that, it was bad admin, but that wasn't the only factor.) Lot of uncertainty. Should I take a kindergarten class if I get an offer? Should I even try to do this again next year?