I would suggest talking to the students' ESOL teacher. I am sure that he/she could give you many great and useful ideas that could benefit your students. ESOL teachers are trained to work with these students, so I would utilize their skills as much as possible.

There are programs available through Google called Natural Reader, which reads passages to students at a natural rate and allows students to stop and go back to unknown words. I believe that you can select the passages and even add questions to the end for students to answer. There is also a program call RazKids, it may be too young for your age group, but it is another read and respond type program (you do have to have a license). Maybe suggest to parents they stay after school or stay in from any activity period they may have. This will be more work for you but hopefully it will help in the long run.

Talk tot he bilingual assistant for more helpful ideas that you can implement

You sound like you are using some great strategies! Do the students have IEPs for language? Check those for accommodations. After speaking with the ESOL teacher or bilingual assistant for more possible solutions, I would provide more visual aids, like graphic organizers. Best of luck!

The first step would be to give the students test and allow them to do the tests by themselves to gather data about how their language is affecting their learning. After you do that, you should hold an emergency meeting with the ELL committee to find a way to provide additional support for the students.