Clothes for Mum Challenge: Basic tshirt pattern

I went very quiet there for a few days because I was busy trying to sort out a tshirt pattern. The first bit was fun, taking measurements (ok so maybe not so fun!) and drafting out the pattern.  Then fitting it and adjusting  it was less fun and more fiddly and I had no idea what I was doing.

This is the tshirt from the initial pattern

As you can see the armhole seams are way too far over and I've got a nasty gape along the shoulder line there.  I drew all over the shirt inside out to indicate where the seam needed to shift to, and and found this very useful video on tissue-fitting a tshirt which suggests that most tshirts need a dart from the armhole. I would never have thought of that because in my experience tshirts don't come with darts! But I put one in and voila! A lovely fit along that seam.

It's an appallingly executed dart and on the pattern I've shifted the position slightly as well, but even like this it makes a big difference. So does bringing that arm seam in.  Of course now it needs a FBA big time as it's too tight across the bust, but fits so nicely along the shoulder I'm pretty pleased.  I have a feeling based on something I read somewhere at some point that you can pin up a dart and cut the fabric from the pinned pattern and incorporate a dart that way but I can't visualise how you'd accommodate the fullness over the bust that way.  Perhaps if I use the seamline as it is when the dart is pinned and then do a FBA on the rest that might do it.  Google Books has an excerpt from The Perfect Fit that has some very useful information on fitting over the bust, including alterations that you could use on a dartless tshirt. The instructions run across two pages horizontally, so you need to look at the top or bottom set of images on successive pages to get the full section - that confused me at first!