How can I change my branch from Infantry to anything else?

With an attitude like that your brief stint in the Infantry will seem like an eternity. If you're a service member your Combat Arms Material. Ever learned of the Battles in the Phillipines prior to the Bataan Death March? The Navy and Army Air Force all became infantry. You need to get a positive mental attitude regarding your branch detail to Infantry. We're only talking approximately three years of your life with the Infantry. You don't have to go Ranger to prove you can lead infantrymen and Women. Every job you mentioned is in support of the Infantry. I worked as a Fire Support Officer the first 13 Months I was in Germany with the Infantry attached. Being assigned infantry you'll have the right to earn the EIB possibly the CIB. Once earned no one can take it away. You're no longer a member of the E-4 Mafia so grow up! Someone in your ROTC Detachment sees something in you. Now shake it off and Lead, Follow or get the hell outta the way!

It will take about 2 seconds for your company commander to pick up on your attitude. I can tell you that the other Lieutenants in your battalion will love having you around as you will be used to round out the BCs senior rater profile. You can go through the next three years miserable, or you can embrace the opportunity. Remember, if you deploy, you will be responsible for the lives of your Soldiers, if you don't think you have what it takes, either go find it, or resign your commission.

You're going to need to grow up. You're going to be leading a platoon of infantrymen - maybe even an Infantrywoman - and your attitude sets the culture of the platoon. You have a couple of years of doing one of the best jobs in the Army. If you roll into it with the mindset that you're only here until you make captain, you might never make captain. You are a Soldier first, officer second, and whatever MOS third.
Sitting on the other side of the desk will give you a greater appreciation of the value of AG once you're the S1. My current S1 was branch detailed Artillery. She's 90 pounds and definitely not Artillery material. But, being a PL gave her an appreciation of how important AG is and she's the hardest working S1 I've ever seen. Use this time to understand your soldiers and their needs and it will make you a good AG.