Keep doubting all you want. It's already part of the record that she had sex with one of her boyfriends on June 28, and that she went to a medical examination sticky with semen and sperm on July 1.
Since Kobe did not ejaculate and the DA is dragging his feet about testing the July-First-on-Katelyn semen and sperm, it is reasonable to assume that the DA suspects that Kobe is not the donor.
This assumption is supported by the fact that Katelyn was wearing underwear stained with sperm and semen when she arrived to the medical exam on July 1. The underwear semen and sperm have already ruled out as belonging to Kobe.
This reminds of a little boy who breaks an expensive vase inside his house, puts the vase together the best he can, and wait for someone else to discover the broken vase.
The last person will be blamed for the broken vase, even though the vase was already broken.
The Bible says that a young woman can be either a door or a fortress with regard to her body.
I'm beginning to suspect that Katelyn is a double-hinged door.