Membership plugin advice, multi user private journals

I am a very novice level WordPress user, and would like to add a feature to a site that would allow users / members to make journal entries. Specifically to log the food they’ve consumed that day. Ideally I’d like the information to be retrievable to the user, but also viewable to an administration (a nutritionist), whom could offer advice / feedback.

I suspect I will need a membership plugin of some sort to make sure users submitted content is private to them and the admin, and I suspect I’ll require some sort of custom form / journal plugin to collect and retrieve the users submissions, but any advice on a method for implementing this would be appreciated.

I know that there are many membership plugins, as well as form plugins,, but do these need to be compatible to operate together?

Thanks in advance for your incites,

Chris