May I suggest that you have someone else measure you for your patterns. Every time you measure yourself, you end up with a mis measure. Sounds like your mom has some experience and it will keep you from buying the wrong size.
Then use your pins to pin the pattern together to help you measure it for any adjustments.
It's not easy to start clothing construction from no experience to such a pattern, but take your time, mark your pattern, and go with the grain!
Good luck, you'll make it!!!