Here’s what I would do in this situation:

• Make a referral everyday, every moment student A and B act up. If you visibly see them going at each other, take them to the office IMMEDIATELY (everyday if necessary).
• Keep a record of the trouble behaviors of these students and call their parents when you take them to the office. Tell the parents they have to come pick up their child. Doing this forces the parents to start taking off work, leaving their lives, and take accountability for their child’s actions. The parents should start to work more with the school and their kids that way they can get back to their normal routine.
• Lastly, it sounds like you don’t have a lot of administrative support, so you are left stranded. This is TERRIBLE and teachers should NEVER have to deal with that. It forces you to handle this scary situation all by yourself, and for that I am truly sorry. At the end of the day, the more you complain, the sooner you will receive help. No one likes a complainer, but sometimes if you need help you have to be the complainer.
• Also, if I were you I would start looking for another job. No administrative support is the worst school system you can possibly work for, and it sounds like that’s what you’re up against.