If i seek help for my mental health under insurance, would they inform my school or future employers about it?

No: Health information is confidential and cannot be released without your written approval; unless of course you threaten someone or give indication that you could "go postal", and then the doctor has an obligation to report you to authorities.

Patient privacy: Your medical records are private, or should be. How insurance companies manage the information they receive may vary, but it is private also. Employers obtain information from many sources, including leave requests, insurance forms, disability claims, etc. The insurance company would not be reporting to future employers or schools, but in some situations you may want to tell them yourself.