Colorblindness is genetic - it's a recessive trait, more common in males, and transmitted through the mother's genes. My son is colorblind, as was my dad. So if she's colorblind, it's been since birth, and there's nothing you can do about it. Same thing for the uncle - he's not "currently colorblind" unless he's had some new and unusual eye problem that has interfered with an ability he had before. There are many kinds of colorblindness - some people can see certain colors and not others. For example, my son is red-green colorblind but sees other colors.
There are simple tests for this and it's useful to know but there's nothing you can do about it. Kids function fine and learn to adapt. It's helpful for the teachers to know. My son had to ask his teachers not to use both red and green markers on the white board - they could use one or the other, and they could use blue and black, but red/green together "danced" around the board for him. They were happy to accommodate, by the way.
However, your child also has trouble with shapes. She's also very young. Kids get these things confused a lot - doesn't mean there's anything wrong with them especially if they are not delayed in other areas. Don't make a special trip in to the doctor, but give them a call before her next check-up and tell them you'd like them to have the pictures available for her to look at to see what she can see.