Is NOBODY wrong in the post ? POST : I'm a president in a club in high school that organizes a lot of events, and part of my job is to assign and distribute projects to the members of the club.

A few days ago, we had a club meeting with the college's management to discuss the progress of our events. Everything was going pretty smoothly until one of the leaders of the project said something that kind of triggered me. ( I'll refer to him as G)

We were suppose to order custom made t-shirts for one of our events. But G said that he already ordered the shirts without consulting us. He has no ideas what  the budget is, and the number of people coming to this event. Admittedly I was kind of pissed but I held my cool until the end of the meeting. I then asked if I could meet him personally after. 

In our one to one conversation, I said:
'Hey, G? Can I ask what is your thought process? What were you thinking?'
He didn't say anything, probably knowing that he did something wrong.

'Look, I'm not mad. But what you done there is very risky. What happens if we overspend?' then I kept going on without him muttering a word.

'Next time, please consult us (the committee) before doing anything. We have a limited budget, so please think properly before you spend. ' 
After that he left without saying another word. 

Was I too harsh? I wasn't aggressive or anything, but AITA for telling him to consult us and think carefully before doing anything? 
