Lisette B6295

I am going to sew view B (tank top w/ built in bra) from the Lisette pattern B6295. I am sewing it out of a cotton knit with spandex to wear as a sleep top. I have not sewn for myself before, just my kids. I have a a small rib cage compared to my cup size. I am excited to make a top that actually fits. Should I just take my chest measurement and sew that size shortening the elastic I put in the bottom of the shelf bra? I know I would have to do a full bust adjustment if it was a woven pattern. Do I have to do that with this pattern? Thanks for any help. Sasha