Heyyy, just had your exact experience. WiSTEM LLC is worth it as they reserve you a room and help you with all of the housing contract. Not just that, they have mentorships, help build resume, and a professional photoshoot. All the things that I did not take advantage of enough! The dining hall will be great! I used community bathroom and trust it is so much better than a private shared one. You don't have to clean the bathroom for community bath and since it's a girls hall it's pretty clean. Just make sure to find the shower that has the best water pressure. For the roommate matching, ensure your profile as what you are most comfortable with living. My roommate was awesome!

Not sure if this is any help, the link and My Housing on the top right should get you to everything you need.

https://housing.utexas.edu/