I am looking to sew a fitted blouse with no waist darts. When using the online sewing pattern designer should I select Bodycon in step one and then Blouse in step two since selecting Bodycon again only includes options with waist darts?

Also what is the size difference between bodycon and fitted?

Finally, in terms of sizing, are there instructions on how to take correct measurements? i.e. what is the difference between bust and underbust?

Thanks

There's a full size guide here - https://www.sewist.com/pages/sizeguide

Bust is sz16, underbust is sz17, waist - sz18, and for hips and full hips we have visuals on the order page.