You obviously care very much about your customers to even go through the trouble of emailing her to try and save her money.
BUT, I would be very upset if I had ordered 12 yards and it came in pieces, even if it was just 2. Imagine if it were someone posting on this board that they walked in Joanns and asked for 3 yards and were given two 1 and 1/2 yard pieces. We would all be saying, "no way".
Personally, I would have LOVED that you emailed me trying to save me money on shipping! That kind of personal service is very hard to find these days. But, if I hadn't responded, for whatever reason, I would rather you go ahead and sent it exactly like I ordered instead of making that decision for me, even though it really was a "better" decision.
Don't beat yourself up over though, you are obviously a very caring business owner and I would love to do business with you!