Once the UTI is clear I would spay her. If she has a history of them I would think going into heat won't help that situation. My friends dog just had pyometra and almost died. $1800 later she is alive and did a complete turn around. I only bring that up because all of those parts are connected and if a dog is prone to bacterial infections in any of those connecting parts, I would want to reduce those chances.
Misty- Samoyed Mix, Tannor- Golden Retriever CGC
Robyn- GSD CGC, TC, Midnite-GSD CGC,TC, Brennan-Golden Retriever CGC, Batman-Husky/Greyhound , Apollo-GSD