I know you are sad or upset but it made me chuckle. It must be your older sister. Is it an older sister? I'm the older sister and my sisters (sadly one died) would always say that they can't do anything as well as I do it. Wasn't true, still isn't true.They thought and still think it is true. If asked my opinion, especially if my sister asks, I give a 100% honest answer. If they would say "Do you like this?". If they made it, even if it was ugly, I would say something positive and nice. You can always say something nice. If they ask "What would you do differently with this?" I would give options thinking they wanted options. Your sister may have only given a different opinion because she thought you wanted a different opinion. I never ask opinions when I am going to make something. I have it in my head what I'm doing and sadly I don't care what anyone else thinks. They aren't making it. If they want a quilt a different way, if they need a machine to do it they can borrow one of mine but they can go ahead and make it themselves.
Your sister probably thought she was being kind offering suggestions but next time do like me and don't ask because it doesn't matter what they think.