Lover’s Knot shirt - This is more of a recipe than a pattern, but it will be very easy to follow.
The pattern is bottom-up, circular shirt with seaming, only to make the neck opening.
Size is dependant on gauge in stockinette stitch and body measurement of largest circumference for shirt to cover. With it being bottom-up construction, this shirt can be as long or as short as you prefer by trying it on as you work the pattern.
I used a merino wool. I recommend using a yarn that will NOT grow over time, merino might grow. Or, mix your merino with a cotton or sock yarn (nylon blend).
I recommend using two 5mm/8US circular needles, OR you could use one 5mm/8US circular needle and a knit holder.
A medium shirt used 126g of yarn; this equates to 521yds/476ms or 1.1 skeins. I expect for a teen, this could be made out of 1 skein; and, for XL 3 skeins.
This pattern uses a stitch pattern from: VOGUEknitting Stitch-a-Day 2012 calendar, Sept 5, Lover’s Knot.

https://drive.google.com/open?id=10OuEdU2W0PijAo_xStbvWT7...