Managing lessons without assistant.

I have been teaching preschool for 10 years. For all these years, we are 1 teacher, 25 pupils (1:25) Each classroom has 1 assistant teacher, which most of their times occupied with foods preparations, helping classroom administrations, kitchen cleanliness, pupils daily register, and other routines.  We are hardly to depend on them to assist during pupils learning activities in the classroom.  So, it is quite struggling for me especially managing 3-4 differentiated groups activities.
I am very thankful for a post by Heidi Butkus on Managing Literacy Center with NO adult help .
I am sure those facing the same problem like me would love to read more about it.
I will try literacy center next year.  Hope it does solve my long years problem.