Store contact form submissions in user accounts

I am looking to create a WordPress site where users can submit their water meter readings (just a number) and then that info goes to the site administrator so they get billed for what they used.

I would like to set it up so users login with an account so they can see the previous meter readings they submitted. Any ideas how to do this? I can set up Contact Form 7 with a database but I don’t know how I could get those contact form submissions to like per account and show the users what they submitted previously.

Any help would be appreciated. Thanks!
Ryan