Mri report says posterocentral disc protrusion at l4/l5 level, compressing thecal sac.compres is in center,in my case is it cauda equina syndrome???

Probably not: You are right in saying the protrusion is in the center and pushing back toward the area where the cauda equina is, but cauda equina syndrome is characterized by really severe back pain usually associated with numbness in the legs and bowel and bladder incontinence or retention. It is not subtle, and usually requires severe compression of the canal, which was not mentioned by you.

No: These words dont add up to cauda equina syndrome this reports touching not compression this is likely a asymptomatic incidental finding cauda equina syndrome is not subtle and involves severe pressure if all nerve roots not touching of the sac good luck