Client Portal for Drupal

Hi Drupal Community

I am using the latest verion of Druapl 7 on a new website in development. I need to build a client portal where the uuse can register and then login - which I've managed to do with ease up till now. Once the user has logged in they need to be able to fill in content which would need to be added to their specific user account. The fields of the content could range from a text field, date field, file attachement, messages between user and admin and calculator fields. This content that the user would fill in is sensitive and personal information to the user which only the Admin would be able to see.

I see that there are a few modules out there, however they either confuse me or are not what I am looking for.

Any help is much appreciated.