I felt much the same way when I first came here. Perhaps even more so when I mismeasured myself and got underwear that were a little too skimpy! 
But over time I realized that the road to sewing satisfaction starts with understanding your own body (or the body of whoever you’re sewing for), and customizing any pattern–on any site–to fit that body the best way possible.
Honestly, FreeSewing gives you the biggest headstart on fitting a pattern to a specific body because the patterns it generates are customized from the beginning! No one–and I really mean not a single person–fits into “standard” pattern sizes because, as Joost said, they are a fiction: completely made up, and different companies have different numbers for each size.
When you start your sewing journey, the first thing you need to do is throw out the concept of RTW (ready-to-wear) clothing and its fictional concept of “standard sizes”. It’ll hold you back more than anything else.
“Standard sizes” were created only a hundred or so years ago, as part of the industrial revolution, when for the first time clothing was made by machine rather than by hand. You’re going back before that time, when clothing was made to fit a specific person.
Ask questions here if you’re not sure how to measure certain things. There are little animated examples, but ask questions if you’re still not clear. People are very friendly here and want you to succeed. Slow down and have fun!