I've been there: both as a student, and then as a busy CNA with students on the floor.
Take a deep breath. Cut yourself some slack. IT'S OK.
Bottom line? DO NOT PUT YOUR LICENSE AT RISK. Do not feel bad for getting a CNA to help transfer a patient who can mostly transfer alone. Standby assists to transfer's are still transfers. What if he was on a new blood pressure medication, and got dizzy upon standing? What if he fell back and hit his head on the rails? You can't take that risk as an unlicensed student - the rules are there for a reason.
Same with the isolation room: the CNA's have training on what PPE (personal protective equipment) is needed, where to obtain it, and how to apply it. YOU DONT. So do not take that risk.
Don't feel bad about having trouble understanding a patient. Many times, you will become familiar with a resident after you have spent time with them - certain gestures, certain sounds, the fact that they are fixated on one or two things.
As for the "no, you need to go" comment: as I said, I've been there as a busy CNA. Sometimes, residents become agitated, and you have to remove the trigger - you can't reason with the resident. Sometimes, I was short with the student CNA's - shooting off orders without explaining the reasoning behind it. I always tried to follow back up with them and assure them they were just fine, but it didn't always happen, and not all health care workers will bother to do so. From what you've said, it sounds like that may be the case here.
When I was a student CNA, I always had nail files and lotion in my pockets. I'd find a resident who was lonely and wanted to talk, and do nail care. Other times, when the patient's were napping, I would fill up the water pitchers and go around placing them in the rooms, taking out trash (even when it wasn't the scheduled time to do so), or go around and straighten up the rooms (not touching resident's belongings, just clearing empty cups, taking out unused linens that pile up, replacing crusty urinals and denture cups, etc) - anything to be out of the hallway standing around. Peeking into denture cups was a big one for me....I could always find dentures that had just been plopped in there without being cleaned, and could at least check off denture care for the day! I would often walk in on a CNA alone doing a bed change or some other task I could assist with for a check-off....the CNA's tended to be more receptive when I magically appeared to help when they needed it, rather than asking them to find me something
Sometimes, I got props from my instructor, because I would find bedrails down, bed alarms off, or trip hazards. Got a special mention for that in my evaluation they used when companies called them for references.
Sounds like you have that mindset already - you just need to pinpoint some tasks to do. It takes time to get to know the "flow" of a unit.
Best of luck to you....remember, you are a student, and this is a new and strange situation. Cut yourself some slack and keep up the good work. Also....when you are a busy CNA with students, remember to smile at them