You stopped accepting being underpaid as normal and got yourself a real system to fix it. That decision alone puts you ahead of where you were an hour ago. Your files are ready below.
Open the main guide and read the Introduction and Chapter 1. This is where you'll see exactly why talented designers keep losing money, even when they're fully booked. Don't skip ahead.
Open the Pricing Calculator Template and run the numbers on your last completed job. Compare what you actually earned to what you should have charged. This one exercise will show you exactly where the leaks are.
Read Chapter 2 for the full Price-Proof Formula, then use it on the very next job you quote. Before you agree to any price with a client, run the numbers first.
Save the Deposit & Payment Terms Template and the "Get Paid" Client Message Scripts somewhere easy to find. You'll need the deposit template the next time a new client wants you to start, and the scripts the moment a client goes quiet on a balance.
This is not something to read once and put away. It works when you apply it, job after job, until pricing correctly and protecting your payment becomes how you naturally work. You already have everything you need. The rest is simply doing it, one job at a time.