Setting aside for the moment you are in an AROTC program, have you researched:
You can earn a commission as an officer in the Coast Guard through the Coast Guard Academy and Officer Candidate School, among other means.
www.military.com
(Unofficial but usually realiable source.)
We have numerous officer programs available, both active duty and reserve.
www.gocoastguard.com
(The official source.)
Now, if you contract through AROTC, you sign a contract that commits you to that path. The Army has invested time and training resources in you and counted on you to deliver the required amount of obligated service after commissioning.
If you are on scholarship, then I believe you can take the money and do this first year without obligation, and walk away from the program without payback. After that, payback is involved after you start sophomore year. You have this year to figure out if this path is for you.
Cross-commissioning is relatively rare; it’s not a usual option. The Coast Guard is a far smaller service and takes in far fewer candidates through any of its commissioning programs. See this current thread; the same issues apply:
Thread 'Transferring Academies'
https://www.serviceacademyforums.com/index.php?threads/transferring-academies.88882/
If you really want to go Coast Guard, there are paths to that dream, but your current status as an AROTC cadet adds multiple layers of difficulty.
Separate the two issues. Do you want to commission as an Army officer? Are okay with it, or not at all anymore? Decide and act accordingly.
Do you want to be a Coast Guard officer? How badly? Determine if this is a transient grass-is-greener dream. Decide and act accordingly.
All questions rhetorical.
Assigned reading: DA Form 597. Read all the fine print.