Awe! The girl kitten is a Tortie. Genetically, she is both black and red. Because of the black, she is classified as a "tortoiseshell' and has no agouti to express tabby stripes in her black hairs. Agouti does not affect red hair, so red cats will always express their tabby pattern in their red hair, as torties do, too.
No white markings on them?
It looks like you're doing a good job with them.