How to Properly Structure My data in Mongo Db

I am having one problem while working on Mongo db with an Node js project, I am creating a Meeting Scheduler project where a user(admin) can create an account and register his company on our project and that company has 1000 members and few teams and members can be a part of multiple teams and some members can be alone not in any team and their are multiple admins with different access

and their is also an data of meetings
Their are Personal meetings of a member with one or multiple members
and also their are Team meetings

Their is also an data of messages
A user can send the message to his Team

Their is also an TODO list of the particulars Teams

So what I tried is storing data in the only one User Model where it has every data about his Team , Personal and Team Meetings and Team Messages I have to store in every User's Collection

The issue in this is that its I know its not at all the Best and Optimized approach to solve this problem and this will consume a lot of memory

Can Anyone please suggest the best way to Store this data like how to store data in different Models/Schemas and how to link them for the best performace and ease to access and perform CRUD operations