I know how you feel. I'm profoundly color blind and I quilt. Shortly after I started quilting I realized I can't do quilts with a zillions of different fabrics/colors. I get paralyzed mentally after many attempts to make it work because I literally can't process all the different colors. I'm also somewhat geometry challenged, so complex quilts are not in my future.
Nonetheless, I do what I consider creative quilting. Creativity isn't all about complexity and color, or even talent, it's about what you do with the gifts God gave you.
My niche is 2, 3, or 4 fabric quilts. Within that niche, I make quilts that I consider creative. It's not easy; I have to audition fabrics and have my DH (or someone who I know is good with color) approve my fabric choices. I'd say my quilts are striking, perhaps more on the modern side than the traditional.
So don't concern yourself with your sister's creativity vs yours. It's the excitement that you felt before you spoke with your sister that makes quilting fun, so show her your quilts after you're finished or don't show them to her at all.
PS: I'm 65 and my sister is 69. We both quilt, but I've been doing it longer, so I've figured out how to do a few more things than she has. She will not take any suggestions from me about anything. Sadly, sibling rivalry will apparently live with us until one of us dies. That makes it hard to share the excitement and joy of quilting with her. Oh, well.