Double-sided back-end development

Hello, I need someone to code the back-end part of our website [login to view URL] It is a premium private tutoring service. I did the front-end by myself using Wordpress + Avada theme and I believe it is fine. But the back-end part seems painful, if not impossible, to do with Wordpress. I need proper register + login + lost password + database functions (with registration confirmation sent to the client's email). Most importantly, I need fully customizable customer accounts, which differ depending on whether it is a parent or a tutor loging in. The parent needs to be able to see some common pdf files but also specific invoices. The tutor needs to be able to see some common pdfs, and declare the number of hours they’ve worked with each student. Absolutely all the texts have to be customizable as the final project will be in French. The billing and the debiting of the parent's account should be automated using Stripe. The debit of the parent's account has to be triggered by the tutor declaring the class. An email asking to confirm the payment by clicking on a button has to be sent to the parent. Once the payment is indeed confirmed by the parent, an invoice should be sent to the same email address and, if possible, stored on the parent's account. If Stripe allows it, the amount debited from the parent's account would automatically be split in two parts: one for the company and one for the tutor. Sincerely,