Hospital Gown

Hi everyone,

    I made this gown for a co-workers little girl who visits the hospital alot. I had a very hard time with this because I ended up making the sleeves just a bit small. The little girl was able to wear it, but I would like some input on how to make bigger sleeves.  The sleeves are hard to see, but I just made one piece pattern. I think when I cut under the arms I do so a little to narrow. How can I fix that problem so next time I don't have the same issue. Thanks

ilovesewingnow