I too struggle with this. I think if you do a search on "copywright" on this site , you'll get lots of hits about the subject.
My take on it would be this...
to make something one time for a friend, and charge them for the materials and your time (altho you won't get full compensation), is OK???
But, to take those same bags, for personal use only, and sell them in a store, wouldn't be OK.
but...bottom line, essentially they are the same.
good luck...but do a search, I am SURE that this topic has been discussed before.
you could also email/write the author of the pattern, and ask how she feels about it.