I'm not sure how to utilize the AI software so would someone be able to use AI to make a realistic 8-9 month pregnancy (belly and boobs) on this girl.

Thank you kindly.

You're in luck, I've been experimenting with trying to get realistic pregnant bodies in Stable Diffusion (specifically the f222 model, it's class for this sort of thing).

The trick is to lower the attention of the word "pregnant" to reduce the weird hand artifacts and missing belly buttons. It also requires a bit of image morphing and upscaling to get it just right.

Hope this is sort of what you wanted, included a comparison.